The costs per load (in cents) of 47 dish-washing detergents tested by a consumer organization are shown here. Find the standard deviation of the sample.
$\begin{array} { c c } \text { Class limits } & \text { Frequency } \ 20 - 28 & 12 \ 29 - 37 & 10 \ 38 - 46 & 14 \ 47 - 55 & 11 \end{array}$
A) 10.0
B) 10.4
C) 10.1
D) 6.2

Question

Quizplus · Accepted Answer

The standard deviation is calculated using the class midpoints and frequencies. The midpoints are 24, 33, 42, and 51. Using these, the mean is calculated, followed by the variance and then the standard deviation, which is approximately 10.1.