The sixth-grade students at Jefferson Middle School took a survey for health class. As part of the survey, they were asked to record how long they spent brushing their teeth before school one morning. This box plot shows the results.

Question

Time brushing teeth (sec.)
40
60
80
100
120
140
What percent of the students spent 60 seconds or longer brushing their teeth?
%

Answer 1

To determine what percent of the students spent 60 seconds or longer brushing their teeth based on the box plot, we need to understand what the box plot represents.

A box plot typically displays the minimum, first quartile (Q1), median (Q2), third quartile (Q3), and maximum values of a data set. The lower 25% of the data will be below Q1, and the upper 25% will be above Q3.

If the box plot shows that the median (Q2) is 80 seconds, Q1 is 60 seconds, and Q3 is 100 seconds, we can derive the following:

• The lower quartile (Q1) indicates that 25% of the students spent less than 60 seconds brushing their teeth.
• This means that 75% of the students spent 60 seconds or longer brushing their teeth.

To find the percentage, we would calculate it as follows:

\[ \text{Percentage of students who spent 60 seconds or longer} = 100% - 25% = 75% \]

Therefore, 75% of the students spent 60 seconds or longer brushing their teeth.