Posted by **Nathan** on Wednesday, March 25, 2009 at 9:16pm.

The time required for a citizen to complete the 2000 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 1 hour?

- Probability -
**drwls**, Wednesday, March 25, 2009 at 9:22pm
97.72%

Use the tool at

http://psych.colorado.edu/~mcclella/java/normal/accurateNormal.html

- Probability -
**Nathan**, Wednesday, March 25, 2009 at 9:25pm
Is there anyway you could explain that to me so I can understand it?

- Probability -
**economyst**, Thursday, March 26, 2009 at 9:19am
1 hour is 20 minutes = 2 standard deviations away from the mean. Your stats book should have a cumulative normal distribution table. Look up 2.0 in the table. I get .9772. Ergo, 97.72% will require less than an hour.

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