The average age of Stokes County school board members over the last 40 years has been 55, but members have ranged from 32 to 70. Use the range rule of thumb to estimate the standard deviation of the members' ages.
A) 19
B) 25.5
C) 9.5
D) 52.3

Question

Quizplus · Accepted Answer

The range rule of thumb estimates the standard deviation as the range divided by 4. The range is 70 - 32 = 38, so the standard deviation is approximately 38 / 4 = 9.5.

The Average Age of Stokes County School Board Members Over