Find the sum of the First $50$ Natural Numbers starting from $11$. Is it from $11-50$ or $11-60$?
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This a simple question yet confusing for me, I found the answer as 1220 by taking sum from $11$ to $50$, by inferring the question as first 50 natural numbers $1,2,3,4,5,6,7,8,9,10,11,...49,50$
and sum starting from 11 which means sum $= 11+12+...+49+50$.
But my friend says otherwise, he took from 11 to 60 and says answer as 1775. Can anyone explain how to infer the word first in the context of maths.
summation word-problem gre-exam natural-numbers
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up vote
2
down vote
favorite
This a simple question yet confusing for me, I found the answer as 1220 by taking sum from $11$ to $50$, by inferring the question as first 50 natural numbers $1,2,3,4,5,6,7,8,9,10,11,...49,50$
and sum starting from 11 which means sum $= 11+12+...+49+50$.
But my friend says otherwise, he took from 11 to 60 and says answer as 1775. Can anyone explain how to infer the word first in the context of maths.
summation word-problem gre-exam natural-numbers
1
Welcome to MSE. For some basic information about writing mathematics at this site see, e.g., basic help on mathjax notation, mathjax tutorial and quick reference, main meta site math tutorial and equation editing how-to.
â José Carlos Santos
Aug 6 at 18:57
I've fixed the title to something more relevant.
â Jam
Aug 6 at 19:41
Pls revert it back or add "find the sum of" to the start.. see the comment from me which has an image snapshot of the exact question, if you change the title into this it will change the meaning of what i am trying to ask in the description.
â Subhassh Mahenthren
Aug 6 at 19:49
@SubhasshMahenthren Done. I was slightly reluctant to include it since I think people were glancing at the "sum of" and not actually focusing on what your question was really regarding.
â Jam
Aug 6 at 20:01
@Jam Oops sry i changed it before i saw your comment. change it whichever way you feel is better or leave if its ok as of now..
â Subhassh Mahenthren
Aug 6 at 20:07
 |Â
show 1 more comment
up vote
2
down vote
favorite
up vote
2
down vote
favorite
This a simple question yet confusing for me, I found the answer as 1220 by taking sum from $11$ to $50$, by inferring the question as first 50 natural numbers $1,2,3,4,5,6,7,8,9,10,11,...49,50$
and sum starting from 11 which means sum $= 11+12+...+49+50$.
But my friend says otherwise, he took from 11 to 60 and says answer as 1775. Can anyone explain how to infer the word first in the context of maths.
summation word-problem gre-exam natural-numbers
This a simple question yet confusing for me, I found the answer as 1220 by taking sum from $11$ to $50$, by inferring the question as first 50 natural numbers $1,2,3,4,5,6,7,8,9,10,11,...49,50$
and sum starting from 11 which means sum $= 11+12+...+49+50$.
But my friend says otherwise, he took from 11 to 60 and says answer as 1775. Can anyone explain how to infer the word first in the context of maths.
summation word-problem gre-exam natural-numbers
edited Aug 6 at 20:26
asked Aug 6 at 18:50
Subhassh Mahenthren
113
113
1
Welcome to MSE. For some basic information about writing mathematics at this site see, e.g., basic help on mathjax notation, mathjax tutorial and quick reference, main meta site math tutorial and equation editing how-to.
â José Carlos Santos
Aug 6 at 18:57
I've fixed the title to something more relevant.
â Jam
Aug 6 at 19:41
Pls revert it back or add "find the sum of" to the start.. see the comment from me which has an image snapshot of the exact question, if you change the title into this it will change the meaning of what i am trying to ask in the description.
â Subhassh Mahenthren
Aug 6 at 19:49
@SubhasshMahenthren Done. I was slightly reluctant to include it since I think people were glancing at the "sum of" and not actually focusing on what your question was really regarding.
â Jam
Aug 6 at 20:01
@Jam Oops sry i changed it before i saw your comment. change it whichever way you feel is better or leave if its ok as of now..
â Subhassh Mahenthren
Aug 6 at 20:07
 |Â
show 1 more comment
1
Welcome to MSE. For some basic information about writing mathematics at this site see, e.g., basic help on mathjax notation, mathjax tutorial and quick reference, main meta site math tutorial and equation editing how-to.
â José Carlos Santos
Aug 6 at 18:57
I've fixed the title to something more relevant.
â Jam
Aug 6 at 19:41
Pls revert it back or add "find the sum of" to the start.. see the comment from me which has an image snapshot of the exact question, if you change the title into this it will change the meaning of what i am trying to ask in the description.
â Subhassh Mahenthren
Aug 6 at 19:49
@SubhasshMahenthren Done. I was slightly reluctant to include it since I think people were glancing at the "sum of" and not actually focusing on what your question was really regarding.
â Jam
Aug 6 at 20:01
@Jam Oops sry i changed it before i saw your comment. change it whichever way you feel is better or leave if its ok as of now..
â Subhassh Mahenthren
Aug 6 at 20:07
1
1
Welcome to MSE. For some basic information about writing mathematics at this site see, e.g., basic help on mathjax notation, mathjax tutorial and quick reference, main meta site math tutorial and equation editing how-to.
â José Carlos Santos
Aug 6 at 18:57
Welcome to MSE. For some basic information about writing mathematics at this site see, e.g., basic help on mathjax notation, mathjax tutorial and quick reference, main meta site math tutorial and equation editing how-to.
â José Carlos Santos
Aug 6 at 18:57
I've fixed the title to something more relevant.
â Jam
Aug 6 at 19:41
I've fixed the title to something more relevant.
â Jam
Aug 6 at 19:41
Pls revert it back or add "find the sum of" to the start.. see the comment from me which has an image snapshot of the exact question, if you change the title into this it will change the meaning of what i am trying to ask in the description.
â Subhassh Mahenthren
Aug 6 at 19:49
Pls revert it back or add "find the sum of" to the start.. see the comment from me which has an image snapshot of the exact question, if you change the title into this it will change the meaning of what i am trying to ask in the description.
â Subhassh Mahenthren
Aug 6 at 19:49
@SubhasshMahenthren Done. I was slightly reluctant to include it since I think people were glancing at the "sum of" and not actually focusing on what your question was really regarding.
â Jam
Aug 6 at 20:01
@SubhasshMahenthren Done. I was slightly reluctant to include it since I think people were glancing at the "sum of" and not actually focusing on what your question was really regarding.
â Jam
Aug 6 at 20:01
@Jam Oops sry i changed it before i saw your comment. change it whichever way you feel is better or leave if its ok as of now..
â Subhassh Mahenthren
Aug 6 at 20:07
@Jam Oops sry i changed it before i saw your comment. change it whichever way you feel is better or leave if its ok as of now..
â Subhassh Mahenthren
Aug 6 at 20:07
 |Â
show 1 more comment
4 Answers
4
active
oldest
votes
up vote
3
down vote
I think there's a bit of ambiguity in the language, so either interpretation is justified. I also think it's just a poorly worded question. The only recourse is to ask whoever set the question or to just let it go - I don't think the intended meaning is really something you can figure out by yourself.
To clarify why I believe both interpretations are valid:
"The first $50$ natural numbers" means $1-50$. So then "The first $50$ natural numbers (starting from $11$)" could mean the same set $1-50$ but starting from $11$ and excluding $1-10$. So $11-50$.
"The natural numbers starting from $11$" means $11,12,ldots$. So then "(The first $50$) natural numbers starting from $11$" could mean the first $50$ elements of this set. So $11-60$.
add a comment |Â
up vote
0
down vote
From a book for GRE practice
I can see how the word "first" is used in a particular context in mathematics. Is that why my interpretation is wrong... or is that my interpretation does not bring logic even by english, that's what i would like to know.. thanks @jam now i know i am not alone in this.
Take a look at the image link attached here, if we see the options everyone will surely come to conclusion my friend is right.. but i wanted to clarify if there is any logical mistake in my interpretation.
add a comment |Â
up vote
0
down vote
Following the link that you provided, we find that the wording in the review book is
Find the sum of first $50$ natural numbers starting from $11$.
This is not Standard English; it should say "of the first" rather than "of first". Hence I have some doubts that you will ever see a question worded exactly like this on an actual GRE exam.
But if the phrase "the first $50$ natural numbers starting from $11$" were to occur on an actual GRE, I probably would interpret it by considering the
"natural numbers starting from $11$" (which are $11, 12, 13, ldots$) and then taking the first $50$ of those.
That is, I would take
the first $50$ members of $n in mathbb N mid n geq 11.$
The alternative, if I first collect the first $50$ natural numbers and then "[start] from $11$", is that the "starting from $11$" part becomes meaningless. I already have a finite set of $50$ numbers, so what does it matter any more where the set "starts"?
If I write $11,12,13,ldots,49,50,1,2,3,ldots,9,10,$
it means exactly the same thing as $1,2,3,ldots,49,50.$
The "starting" point of the sum of a finite set is just as meaningless,
since addition is commutative.
This logic does not prove that my interpretation is correct--I believe the wording is ambiguous--but I find the other interpretation a highly unnatural use of the natural English language.
Yes! "of the first" seems to makes some difference, thank you.
â Subhassh Mahenthren
Aug 7 at 12:24
add a comment |Â
up vote
-2
down vote
There's a high school formula for the sum of consecutive terms in an arithmetic sequence: it is equal to the number of terms, times the arithmetic mean of the first and last term
.
Here the first term is $11$ and $50$th term is $60$, so the sum is
$$50timesfrac11+602=1775.$$
add a comment |Â
4 Answers
4
active
oldest
votes
4 Answers
4
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
3
down vote
I think there's a bit of ambiguity in the language, so either interpretation is justified. I also think it's just a poorly worded question. The only recourse is to ask whoever set the question or to just let it go - I don't think the intended meaning is really something you can figure out by yourself.
To clarify why I believe both interpretations are valid:
"The first $50$ natural numbers" means $1-50$. So then "The first $50$ natural numbers (starting from $11$)" could mean the same set $1-50$ but starting from $11$ and excluding $1-10$. So $11-50$.
"The natural numbers starting from $11$" means $11,12,ldots$. So then "(The first $50$) natural numbers starting from $11$" could mean the first $50$ elements of this set. So $11-60$.
add a comment |Â
up vote
3
down vote
I think there's a bit of ambiguity in the language, so either interpretation is justified. I also think it's just a poorly worded question. The only recourse is to ask whoever set the question or to just let it go - I don't think the intended meaning is really something you can figure out by yourself.
To clarify why I believe both interpretations are valid:
"The first $50$ natural numbers" means $1-50$. So then "The first $50$ natural numbers (starting from $11$)" could mean the same set $1-50$ but starting from $11$ and excluding $1-10$. So $11-50$.
"The natural numbers starting from $11$" means $11,12,ldots$. So then "(The first $50$) natural numbers starting from $11$" could mean the first $50$ elements of this set. So $11-60$.
add a comment |Â
up vote
3
down vote
up vote
3
down vote
I think there's a bit of ambiguity in the language, so either interpretation is justified. I also think it's just a poorly worded question. The only recourse is to ask whoever set the question or to just let it go - I don't think the intended meaning is really something you can figure out by yourself.
To clarify why I believe both interpretations are valid:
"The first $50$ natural numbers" means $1-50$. So then "The first $50$ natural numbers (starting from $11$)" could mean the same set $1-50$ but starting from $11$ and excluding $1-10$. So $11-50$.
"The natural numbers starting from $11$" means $11,12,ldots$. So then "(The first $50$) natural numbers starting from $11$" could mean the first $50$ elements of this set. So $11-60$.
I think there's a bit of ambiguity in the language, so either interpretation is justified. I also think it's just a poorly worded question. The only recourse is to ask whoever set the question or to just let it go - I don't think the intended meaning is really something you can figure out by yourself.
To clarify why I believe both interpretations are valid:
"The first $50$ natural numbers" means $1-50$. So then "The first $50$ natural numbers (starting from $11$)" could mean the same set $1-50$ but starting from $11$ and excluding $1-10$. So $11-50$.
"The natural numbers starting from $11$" means $11,12,ldots$. So then "(The first $50$) natural numbers starting from $11$" could mean the first $50$ elements of this set. So $11-60$.
edited Aug 6 at 21:46
answered Aug 6 at 18:54
Jam
4,25611230
4,25611230
add a comment |Â
add a comment |Â
up vote
0
down vote
From a book for GRE practice
I can see how the word "first" is used in a particular context in mathematics. Is that why my interpretation is wrong... or is that my interpretation does not bring logic even by english, that's what i would like to know.. thanks @jam now i know i am not alone in this.
Take a look at the image link attached here, if we see the options everyone will surely come to conclusion my friend is right.. but i wanted to clarify if there is any logical mistake in my interpretation.
add a comment |Â
up vote
0
down vote
From a book for GRE practice
I can see how the word "first" is used in a particular context in mathematics. Is that why my interpretation is wrong... or is that my interpretation does not bring logic even by english, that's what i would like to know.. thanks @jam now i know i am not alone in this.
Take a look at the image link attached here, if we see the options everyone will surely come to conclusion my friend is right.. but i wanted to clarify if there is any logical mistake in my interpretation.
add a comment |Â
up vote
0
down vote
up vote
0
down vote
From a book for GRE practice
I can see how the word "first" is used in a particular context in mathematics. Is that why my interpretation is wrong... or is that my interpretation does not bring logic even by english, that's what i would like to know.. thanks @jam now i know i am not alone in this.
Take a look at the image link attached here, if we see the options everyone will surely come to conclusion my friend is right.. but i wanted to clarify if there is any logical mistake in my interpretation.
From a book for GRE practice
I can see how the word "first" is used in a particular context in mathematics. Is that why my interpretation is wrong... or is that my interpretation does not bring logic even by english, that's what i would like to know.. thanks @jam now i know i am not alone in this.
Take a look at the image link attached here, if we see the options everyone will surely come to conclusion my friend is right.. but i wanted to clarify if there is any logical mistake in my interpretation.
edited Aug 6 at 19:43
user579082
answered Aug 6 at 19:09
Subhassh Mahenthren
113
113
add a comment |Â
add a comment |Â
up vote
0
down vote
Following the link that you provided, we find that the wording in the review book is
Find the sum of first $50$ natural numbers starting from $11$.
This is not Standard English; it should say "of the first" rather than "of first". Hence I have some doubts that you will ever see a question worded exactly like this on an actual GRE exam.
But if the phrase "the first $50$ natural numbers starting from $11$" were to occur on an actual GRE, I probably would interpret it by considering the
"natural numbers starting from $11$" (which are $11, 12, 13, ldots$) and then taking the first $50$ of those.
That is, I would take
the first $50$ members of $n in mathbb N mid n geq 11.$
The alternative, if I first collect the first $50$ natural numbers and then "[start] from $11$", is that the "starting from $11$" part becomes meaningless. I already have a finite set of $50$ numbers, so what does it matter any more where the set "starts"?
If I write $11,12,13,ldots,49,50,1,2,3,ldots,9,10,$
it means exactly the same thing as $1,2,3,ldots,49,50.$
The "starting" point of the sum of a finite set is just as meaningless,
since addition is commutative.
This logic does not prove that my interpretation is correct--I believe the wording is ambiguous--but I find the other interpretation a highly unnatural use of the natural English language.
Yes! "of the first" seems to makes some difference, thank you.
â Subhassh Mahenthren
Aug 7 at 12:24
add a comment |Â
up vote
0
down vote
Following the link that you provided, we find that the wording in the review book is
Find the sum of first $50$ natural numbers starting from $11$.
This is not Standard English; it should say "of the first" rather than "of first". Hence I have some doubts that you will ever see a question worded exactly like this on an actual GRE exam.
But if the phrase "the first $50$ natural numbers starting from $11$" were to occur on an actual GRE, I probably would interpret it by considering the
"natural numbers starting from $11$" (which are $11, 12, 13, ldots$) and then taking the first $50$ of those.
That is, I would take
the first $50$ members of $n in mathbb N mid n geq 11.$
The alternative, if I first collect the first $50$ natural numbers and then "[start] from $11$", is that the "starting from $11$" part becomes meaningless. I already have a finite set of $50$ numbers, so what does it matter any more where the set "starts"?
If I write $11,12,13,ldots,49,50,1,2,3,ldots,9,10,$
it means exactly the same thing as $1,2,3,ldots,49,50.$
The "starting" point of the sum of a finite set is just as meaningless,
since addition is commutative.
This logic does not prove that my interpretation is correct--I believe the wording is ambiguous--but I find the other interpretation a highly unnatural use of the natural English language.
Yes! "of the first" seems to makes some difference, thank you.
â Subhassh Mahenthren
Aug 7 at 12:24
add a comment |Â
up vote
0
down vote
up vote
0
down vote
Following the link that you provided, we find that the wording in the review book is
Find the sum of first $50$ natural numbers starting from $11$.
This is not Standard English; it should say "of the first" rather than "of first". Hence I have some doubts that you will ever see a question worded exactly like this on an actual GRE exam.
But if the phrase "the first $50$ natural numbers starting from $11$" were to occur on an actual GRE, I probably would interpret it by considering the
"natural numbers starting from $11$" (which are $11, 12, 13, ldots$) and then taking the first $50$ of those.
That is, I would take
the first $50$ members of $n in mathbb N mid n geq 11.$
The alternative, if I first collect the first $50$ natural numbers and then "[start] from $11$", is that the "starting from $11$" part becomes meaningless. I already have a finite set of $50$ numbers, so what does it matter any more where the set "starts"?
If I write $11,12,13,ldots,49,50,1,2,3,ldots,9,10,$
it means exactly the same thing as $1,2,3,ldots,49,50.$
The "starting" point of the sum of a finite set is just as meaningless,
since addition is commutative.
This logic does not prove that my interpretation is correct--I believe the wording is ambiguous--but I find the other interpretation a highly unnatural use of the natural English language.
Following the link that you provided, we find that the wording in the review book is
Find the sum of first $50$ natural numbers starting from $11$.
This is not Standard English; it should say "of the first" rather than "of first". Hence I have some doubts that you will ever see a question worded exactly like this on an actual GRE exam.
But if the phrase "the first $50$ natural numbers starting from $11$" were to occur on an actual GRE, I probably would interpret it by considering the
"natural numbers starting from $11$" (which are $11, 12, 13, ldots$) and then taking the first $50$ of those.
That is, I would take
the first $50$ members of $n in mathbb N mid n geq 11.$
The alternative, if I first collect the first $50$ natural numbers and then "[start] from $11$", is that the "starting from $11$" part becomes meaningless. I already have a finite set of $50$ numbers, so what does it matter any more where the set "starts"?
If I write $11,12,13,ldots,49,50,1,2,3,ldots,9,10,$
it means exactly the same thing as $1,2,3,ldots,49,50.$
The "starting" point of the sum of a finite set is just as meaningless,
since addition is commutative.
This logic does not prove that my interpretation is correct--I believe the wording is ambiguous--but I find the other interpretation a highly unnatural use of the natural English language.
answered Aug 6 at 20:47
David K
48.3k340107
48.3k340107
Yes! "of the first" seems to makes some difference, thank you.
â Subhassh Mahenthren
Aug 7 at 12:24
add a comment |Â
Yes! "of the first" seems to makes some difference, thank you.
â Subhassh Mahenthren
Aug 7 at 12:24
Yes! "of the first" seems to makes some difference, thank you.
â Subhassh Mahenthren
Aug 7 at 12:24
Yes! "of the first" seems to makes some difference, thank you.
â Subhassh Mahenthren
Aug 7 at 12:24
add a comment |Â
up vote
-2
down vote
There's a high school formula for the sum of consecutive terms in an arithmetic sequence: it is equal to the number of terms, times the arithmetic mean of the first and last term
.
Here the first term is $11$ and $50$th term is $60$, so the sum is
$$50timesfrac11+602=1775.$$
add a comment |Â
up vote
-2
down vote
There's a high school formula for the sum of consecutive terms in an arithmetic sequence: it is equal to the number of terms, times the arithmetic mean of the first and last term
.
Here the first term is $11$ and $50$th term is $60$, so the sum is
$$50timesfrac11+602=1775.$$
add a comment |Â
up vote
-2
down vote
up vote
-2
down vote
There's a high school formula for the sum of consecutive terms in an arithmetic sequence: it is equal to the number of terms, times the arithmetic mean of the first and last term
.
Here the first term is $11$ and $50$th term is $60$, so the sum is
$$50timesfrac11+602=1775.$$
There's a high school formula for the sum of consecutive terms in an arithmetic sequence: it is equal to the number of terms, times the arithmetic mean of the first and last term
.
Here the first term is $11$ and $50$th term is $60$, so the sum is
$$50timesfrac11+602=1775.$$
edited Aug 6 at 21:21
answered Aug 6 at 19:02
Bernard
110k635103
110k635103
add a comment |Â
add a comment |Â
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1
Welcome to MSE. For some basic information about writing mathematics at this site see, e.g., basic help on mathjax notation, mathjax tutorial and quick reference, main meta site math tutorial and equation editing how-to.
â José Carlos Santos
Aug 6 at 18:57
I've fixed the title to something more relevant.
â Jam
Aug 6 at 19:41
Pls revert it back or add "find the sum of" to the start.. see the comment from me which has an image snapshot of the exact question, if you change the title into this it will change the meaning of what i am trying to ask in the description.
â Subhassh Mahenthren
Aug 6 at 19:49
@SubhasshMahenthren Done. I was slightly reluctant to include it since I think people were glancing at the "sum of" and not actually focusing on what your question was really regarding.
â Jam
Aug 6 at 20:01
@Jam Oops sry i changed it before i saw your comment. change it whichever way you feel is better or leave if its ok as of now..
â Subhassh Mahenthren
Aug 6 at 20:07