(Box and Whisker Plot Problem) Why is the answer choice 3 instead of choice 2?

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(Look at the link below)
Problem #$6$ has me confused. The answer key of the textbook I am using states that the answer is choice $3$. But shouldn't the answer be choice $2$ ( $7$ students ) because the numbers, $81$ through $88$, are below Q$3$?



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  • I believe you are correct: the given range is between the median and the 3rd quartile, which contains $1/4$ of the students.
    – angryavian
    Jul 30 at 3:42










  • The question in the book is not well put (see my answer below). A possible meaningful question would be "AT LEAST how many students scored from 81 to 88?" Then, you can derive the answer 7 by applying the properties of the quartiles as follows: AT LEAST 14 scores ($50%$ of the scores) must be greater than or equal to the second quartile (the median). AT MOST 7 scores ($25%$ of the scores) can be greater than the third quartile (assumed to be 88). So, AT LEAST 7 students scored from 81 to 88.
    – trancelocation
    Jul 31 at 6:23















up vote
0
down vote

favorite












(Look at the link below)
Problem #$6$ has me confused. The answer key of the textbook I am using states that the answer is choice $3$. But shouldn't the answer be choice $2$ ( $7$ students ) because the numbers, $81$ through $88$, are below Q$3$?



enter image description here







share|cite|improve this question





















  • I believe you are correct: the given range is between the median and the 3rd quartile, which contains $1/4$ of the students.
    – angryavian
    Jul 30 at 3:42










  • The question in the book is not well put (see my answer below). A possible meaningful question would be "AT LEAST how many students scored from 81 to 88?" Then, you can derive the answer 7 by applying the properties of the quartiles as follows: AT LEAST 14 scores ($50%$ of the scores) must be greater than or equal to the second quartile (the median). AT MOST 7 scores ($25%$ of the scores) can be greater than the third quartile (assumed to be 88). So, AT LEAST 7 students scored from 81 to 88.
    – trancelocation
    Jul 31 at 6:23













up vote
0
down vote

favorite









up vote
0
down vote

favorite











(Look at the link below)
Problem #$6$ has me confused. The answer key of the textbook I am using states that the answer is choice $3$. But shouldn't the answer be choice $2$ ( $7$ students ) because the numbers, $81$ through $88$, are below Q$3$?



enter image description here







share|cite|improve this question













(Look at the link below)
Problem #$6$ has me confused. The answer key of the textbook I am using states that the answer is choice $3$. But shouldn't the answer be choice $2$ ( $7$ students ) because the numbers, $81$ through $88$, are below Q$3$?



enter image description here









share|cite|improve this question












share|cite|improve this question




share|cite|improve this question








edited Jul 30 at 4:51









高田航

1,116318




1,116318









asked Jul 30 at 3:40









AniJan

113




113











  • I believe you are correct: the given range is between the median and the 3rd quartile, which contains $1/4$ of the students.
    – angryavian
    Jul 30 at 3:42










  • The question in the book is not well put (see my answer below). A possible meaningful question would be "AT LEAST how many students scored from 81 to 88?" Then, you can derive the answer 7 by applying the properties of the quartiles as follows: AT LEAST 14 scores ($50%$ of the scores) must be greater than or equal to the second quartile (the median). AT MOST 7 scores ($25%$ of the scores) can be greater than the third quartile (assumed to be 88). So, AT LEAST 7 students scored from 81 to 88.
    – trancelocation
    Jul 31 at 6:23

















  • I believe you are correct: the given range is between the median and the 3rd quartile, which contains $1/4$ of the students.
    – angryavian
    Jul 30 at 3:42










  • The question in the book is not well put (see my answer below). A possible meaningful question would be "AT LEAST how many students scored from 81 to 88?" Then, you can derive the answer 7 by applying the properties of the quartiles as follows: AT LEAST 14 scores ($50%$ of the scores) must be greater than or equal to the second quartile (the median). AT MOST 7 scores ($25%$ of the scores) can be greater than the third quartile (assumed to be 88). So, AT LEAST 7 students scored from 81 to 88.
    – trancelocation
    Jul 31 at 6:23
















I believe you are correct: the given range is between the median and the 3rd quartile, which contains $1/4$ of the students.
– angryavian
Jul 30 at 3:42




I believe you are correct: the given range is between the median and the 3rd quartile, which contains $1/4$ of the students.
– angryavian
Jul 30 at 3:42












The question in the book is not well put (see my answer below). A possible meaningful question would be "AT LEAST how many students scored from 81 to 88?" Then, you can derive the answer 7 by applying the properties of the quartiles as follows: AT LEAST 14 scores ($50%$ of the scores) must be greater than or equal to the second quartile (the median). AT MOST 7 scores ($25%$ of the scores) can be greater than the third quartile (assumed to be 88). So, AT LEAST 7 students scored from 81 to 88.
– trancelocation
Jul 31 at 6:23





The question in the book is not well put (see my answer below). A possible meaningful question would be "AT LEAST how many students scored from 81 to 88?" Then, you can derive the answer 7 by applying the properties of the quartiles as follows: AT LEAST 14 scores ($50%$ of the scores) must be greater than or equal to the second quartile (the median). AT MOST 7 scores ($25%$ of the scores) can be greater than the third quartile (assumed to be 88). So, AT LEAST 7 students scored from 81 to 88.
– trancelocation
Jul 31 at 6:23











2 Answers
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up vote
3
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Yes, you are correct. The plot shows that the median ($2$nd quartile) is $81$, and that the $3$rd quartile is at $88$, so this range should contain exactly $28(0.25)=7$ students.






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    up vote
    1
    down vote













    The question cannot be answered from the given box plot.



    Example:



    Any ordered score set for $28$ students of the following type would produce the same box plot:



    (I have difficulty to read the $Q_3$ from your picture, so I assume it to be $Q_3= 88$.)
    $$beginpmatrix
    Place: & 1 & cdots & 7 & 8 & cdots & 14 & 15 & cdots & 21 & 22 & cdots & 28 \
    Score: & 62 & cdots & 71 & 71 & cdots & 81 & 81 & cdots & 88 & 88 & cdots & 92
    endpmatrix$$



    This would give possible numbers of scores from 81 to 88 ranging from 9 to 19.



    If we assume that $Q_3 = fracx_21+x_222$, then consider the follwoing score set:
    $$beginpmatrix
    Place: & 1 & cdots & 7 & 8 & cdots & 14 & 15 & cdots & 21 & 22 & cdots & 28 \
    Score: & 62 & cdots & 71 & 71 & cdots & 80 & 82 & cdots & 87 & 89 & cdots & 92
    endpmatrix$$
    This would give the answer of 7 scores ranging from 81 to 88.






    share|cite|improve this answer





















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      2 Answers
      2






      active

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      2 Answers
      2






      active

      oldest

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      active

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      active

      oldest

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      up vote
      3
      down vote













      Yes, you are correct. The plot shows that the median ($2$nd quartile) is $81$, and that the $3$rd quartile is at $88$, so this range should contain exactly $28(0.25)=7$ students.






      share|cite|improve this answer

























        up vote
        3
        down vote













        Yes, you are correct. The plot shows that the median ($2$nd quartile) is $81$, and that the $3$rd quartile is at $88$, so this range should contain exactly $28(0.25)=7$ students.






        share|cite|improve this answer























          up vote
          3
          down vote










          up vote
          3
          down vote









          Yes, you are correct. The plot shows that the median ($2$nd quartile) is $81$, and that the $3$rd quartile is at $88$, so this range should contain exactly $28(0.25)=7$ students.






          share|cite|improve this answer













          Yes, you are correct. The plot shows that the median ($2$nd quartile) is $81$, and that the $3$rd quartile is at $88$, so this range should contain exactly $28(0.25)=7$ students.







          share|cite|improve this answer













          share|cite|improve this answer



          share|cite|improve this answer











          answered Jul 30 at 3:45









          高田航

          1,116318




          1,116318




















              up vote
              1
              down vote













              The question cannot be answered from the given box plot.



              Example:



              Any ordered score set for $28$ students of the following type would produce the same box plot:



              (I have difficulty to read the $Q_3$ from your picture, so I assume it to be $Q_3= 88$.)
              $$beginpmatrix
              Place: & 1 & cdots & 7 & 8 & cdots & 14 & 15 & cdots & 21 & 22 & cdots & 28 \
              Score: & 62 & cdots & 71 & 71 & cdots & 81 & 81 & cdots & 88 & 88 & cdots & 92
              endpmatrix$$



              This would give possible numbers of scores from 81 to 88 ranging from 9 to 19.



              If we assume that $Q_3 = fracx_21+x_222$, then consider the follwoing score set:
              $$beginpmatrix
              Place: & 1 & cdots & 7 & 8 & cdots & 14 & 15 & cdots & 21 & 22 & cdots & 28 \
              Score: & 62 & cdots & 71 & 71 & cdots & 80 & 82 & cdots & 87 & 89 & cdots & 92
              endpmatrix$$
              This would give the answer of 7 scores ranging from 81 to 88.






              share|cite|improve this answer

























                up vote
                1
                down vote













                The question cannot be answered from the given box plot.



                Example:



                Any ordered score set for $28$ students of the following type would produce the same box plot:



                (I have difficulty to read the $Q_3$ from your picture, so I assume it to be $Q_3= 88$.)
                $$beginpmatrix
                Place: & 1 & cdots & 7 & 8 & cdots & 14 & 15 & cdots & 21 & 22 & cdots & 28 \
                Score: & 62 & cdots & 71 & 71 & cdots & 81 & 81 & cdots & 88 & 88 & cdots & 92
                endpmatrix$$



                This would give possible numbers of scores from 81 to 88 ranging from 9 to 19.



                If we assume that $Q_3 = fracx_21+x_222$, then consider the follwoing score set:
                $$beginpmatrix
                Place: & 1 & cdots & 7 & 8 & cdots & 14 & 15 & cdots & 21 & 22 & cdots & 28 \
                Score: & 62 & cdots & 71 & 71 & cdots & 80 & 82 & cdots & 87 & 89 & cdots & 92
                endpmatrix$$
                This would give the answer of 7 scores ranging from 81 to 88.






                share|cite|improve this answer























                  up vote
                  1
                  down vote










                  up vote
                  1
                  down vote









                  The question cannot be answered from the given box plot.



                  Example:



                  Any ordered score set for $28$ students of the following type would produce the same box plot:



                  (I have difficulty to read the $Q_3$ from your picture, so I assume it to be $Q_3= 88$.)
                  $$beginpmatrix
                  Place: & 1 & cdots & 7 & 8 & cdots & 14 & 15 & cdots & 21 & 22 & cdots & 28 \
                  Score: & 62 & cdots & 71 & 71 & cdots & 81 & 81 & cdots & 88 & 88 & cdots & 92
                  endpmatrix$$



                  This would give possible numbers of scores from 81 to 88 ranging from 9 to 19.



                  If we assume that $Q_3 = fracx_21+x_222$, then consider the follwoing score set:
                  $$beginpmatrix
                  Place: & 1 & cdots & 7 & 8 & cdots & 14 & 15 & cdots & 21 & 22 & cdots & 28 \
                  Score: & 62 & cdots & 71 & 71 & cdots & 80 & 82 & cdots & 87 & 89 & cdots & 92
                  endpmatrix$$
                  This would give the answer of 7 scores ranging from 81 to 88.






                  share|cite|improve this answer













                  The question cannot be answered from the given box plot.



                  Example:



                  Any ordered score set for $28$ students of the following type would produce the same box plot:



                  (I have difficulty to read the $Q_3$ from your picture, so I assume it to be $Q_3= 88$.)
                  $$beginpmatrix
                  Place: & 1 & cdots & 7 & 8 & cdots & 14 & 15 & cdots & 21 & 22 & cdots & 28 \
                  Score: & 62 & cdots & 71 & 71 & cdots & 81 & 81 & cdots & 88 & 88 & cdots & 92
                  endpmatrix$$



                  This would give possible numbers of scores from 81 to 88 ranging from 9 to 19.



                  If we assume that $Q_3 = fracx_21+x_222$, then consider the follwoing score set:
                  $$beginpmatrix
                  Place: & 1 & cdots & 7 & 8 & cdots & 14 & 15 & cdots & 21 & 22 & cdots & 28 \
                  Score: & 62 & cdots & 71 & 71 & cdots & 80 & 82 & cdots & 87 & 89 & cdots & 92
                  endpmatrix$$
                  This would give the answer of 7 scores ranging from 81 to 88.







                  share|cite|improve this answer













                  share|cite|improve this answer



                  share|cite|improve this answer











                  answered Jul 30 at 7:45









                  trancelocation

                  4,5701413




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