Question

a random sample of students at north high school were polled on whether they prefer a 15 - minute break between classes in the morning or in the afternoon. the results are shown in the frequency table. what is the joint relative frequency for 11th graders who want the break in the afternoon? round to the nearest percent.

	morning	afternoon	total
11th	16	25	41
12th	19	20	39
total	56	62	118

21%
25%
40%
61%

Explanation:

Step1: Recall joint - relative frequency formula

Joint relative frequency = $\frac{\text{Frequency in the cell}}{\text{Total number of data points}}$

Step2: Identify relevant values

The frequency of 11th - graders who want the break in the afternoon is 25, and the total number of students is 118.

Step3: Calculate joint relative frequency

Joint relative frequency = $\frac{25}{118}\approx0.212$

Step4: Convert to percentage

$0.212\times100 = 21.2\%$. Rounding to the nearest percent gives 21%.

Answer:

21%