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. What proportion of the citizens will require less than one hour?
A)0.4772
B)0.9772
C)0.9974
D)0.9997

Question

Quizplus · Accepted Answer

To find the proportion of citizens who will require less than one hour, we need to find the z-score for one hour (60 minutes) and then find the area to the left of that value in the standard normal distribution table.

z = (60 - 40) / 10 = 2

The area to the left of z = 2 is 0.9772. This means that about 97.72% of the citizens will require less than one hour to complete the census long form. Therefore, the best answer is B: 0.9772.

The Time Required for a Citizen to Complete the 2010