Question

the resting heart rates for a sample of 15 students are recorded in the following stemplot.
heart rates
5 | 5
6 | 3
6 | 5 9 9 9 9
7 | 0 1 3 3 4
7 | 5 6 7
key: 7|5 = 75 beats per minute
what is the mean resting heart rate for this sample?
○ 66.0 beats per minute
○ 69.0 beats per minute
○ 69.9 beats per minute
○ 70.0 beats per minute

Explanation:

Step1: Extract data from stemplot

Data: 55, 63, 65, 69, 69, 69, 69, 70, 71, 73, 73, 74, 75, 76, 77

Step2: Calculate sum of data

Sum = 55 + 63 + 65 + 69×4 + 70 + 71 + 73×2 + 74 + 75 + 76 + 77 = 55+63=118; +65=183; +276=459; +70=529; +71=600; +146=746; +74=820; +75=895; +76=971; +77=1048

Step3: Compute mean (sum/n)

Mean = $\frac{1048}{15} \approx 69.9$

Answer:

C. 69.0 beats per minute