Question

16 mark for review
the list gives the speeds, in miles per hour, of 7 serves made by a professional tennis player.
102, 119, 119, 121, 152, 156, 156
what is the mean speed, in miles per hour, of these 7 serves?
a 156
b 132
c 121
d 119

Explanation:

Step1: Calculate the sum of the speeds

$$102 + 119+119+121+152+156+156$$
$$=(102 + 121)+(119\times2)+(152)+(156\times2)$$
$$=223+238 + 152+312$$
$$=(223+238)+(152+312)$$
$$=461+464$$
$$=925$$

Step2: Calculate the mean

The formula for the mean $\bar{x}=\frac{\sum_{i = 1}^{n}x_{i}}{n}$, where $n = 7$ (the number of data - points) and $\sum_{i=1}^{n}x_{i}=925$.
So, $\bar{x}=\frac{925}{7}=132.14\approx132$

Answer:

B. 132