**1. The problem statement, all variables and given/known data**

A geiger counter measures 750 counts in 5 min

a) determine the average counting rate and the standard deviation of the counting rate.

b) find the relative error

c) How long would you want to count to get a relative error of 1%?

**2. Relevant equations**

standard deviation = [itex]\sqrt{}navg[/itex]

relative error = δx/x

**3. The attempt at a solution**

The average counting rate is 750/5 which is 150 counts / min and the standard deviation is the square root of that which is 12.247. The relative error is 12.247/150 which is .0816 which is 8.16%

I’m not sure how to determine how long you would want to count to get a relative error of 1%

http://ift.tt/1hxuYJi