If the number of parking spots at urban grocery stores is uniformly distributed over the interval 90 to 140, inclusively (90 $\le$ x $\le$140), then the standard deviation of this distribution is approximately __________________.
A)4.16
B)50
C)14.4
D)7.07
E)28.2

Question

Quizplus · Accepted Answer

The formula for the standard deviation of a uniform distribution is (b-a) / √12, where a and b are the minimum and maximum values of the interval. 
In this case, a = 90 and b = 140, so the standard deviation is (140-90) / √12 = 14.37, which rounds to 14.4. Therefore, the answer is C.

If the Number of Parking Spots at Urban Grocery Stores ≤\le≤

If the Number of Parking Spots at Urban Grocery Stores $\le$