Question

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. time brushing teeth (sec.) what percent of the students spent 60 seconds or longer brushing their teeth? %

Explanation:

Step1: Recall the property of box - plot

In a box - plot, the leftmost whisker represents the minimum value, the left edge of the box represents the first quartile ($Q_1$), the line inside the box represents the median ($Q_2$), the right edge of the box represents the third quartile ($Q_3$), and the rightmost whisker represents the maximum value. The box (from $Q_1$ to $Q_3$) contains 50% of the data, and each whisker (from minimum to $Q_1$ and from $Q_3$ to maximum) contains 25% of the data.

Step2: Analyze the value of 60 seconds

The value of 60 seconds is the first quartile ($Q_1$). The data to the right of $Q_1$ (including the box and the right - hand whisker) represents the percentage of data that is greater than or equal to $Q_1$.
Since the data from $Q_1$ to the end (maximum) is $Q_1$ to $Q_2$ (25%), $Q_2$ to $Q_3$ (25%), and $Q_3$ to maximum (25%).

Answer:

75%