Question

Mr. Garcia asked the members of his health class how many days last week they exercised for at least 30 minutes. The results are summarized in the following bar graph, where the heights of the bars represent the number of students.

What was the mean number of days of exercise last week, rounded to the nearest hundredth, reported by the students in Mr. Garcia's class?

$3.50$

$3.57$

$4.36$

$4.50$

$5.00$

Video solution:

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Written solution:

Counting the number of each occurrence, we can see that there are 1 $1$ s, 3 $2$ s, 2 $3$ s, 6 $4$ s, 8 $5$ s, 3 $6$ s, and 2 $7$ s.

Therefore, there are $1+3+2+6+8+3+2 = 25$ students in total.

Therefore, the total number of days of exercise is $\begin{align*}&1\cdot1+3\cdot2 + 2\cdot 3 + 6\cdot 4 \\ &+ 8\cdot 5 + 3\cdot 6 + 2\cdot 7 \\ &= 109\end{align*}$

The mean number of days of exercise is defined as the total number of days of exercise divided by the total number of students, where: \dfrac{\text{total days}}{\text{# students}} = \dfrac{109}{25} \approx 4.36

Thus, C is the correct answer.

2018 AMC 8 Problem 8

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Written solution:

Problem 8 in Other Years