The time required for a citizen to complete the 2010 U.S. Census "long" form is normally distributed with a mean of 40 minutes and a standard deviation of 10 minutes. The slowest 10 percent of the citizens would need at least how many minutes to complete the form?
A)27.2
B)35.8
C)52.8
D)59.6 Using Excel =NORM.INV(.90,40,10) = 52.82, or 40 + 1.282(10) = 52.82 using AppendixC.

Question

Quizplus · Accepted Answer

By using the formula for the inverse normal distribution, we can find that the slowest 10% of citizens would need at least 52.82 minutes to complete the form. However, since time values cannot be negative, we round up to the nearest whole number and get 53 minutes. Therefore, the best choice is C.

The Time Required for a Citizen to Complete the 2010