Question 265610
My friend works on computers his average time is 4 hours with a 1 hour standard deviation 
1 What is the chance that he works on a computer from his average to 5 hours
Ans: 5 is 1 standard deviation to the right of the mean.
P(4 < x < 5) = 0.34
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2 What is the chance that he works on a computer from 3 hours to his average
Ans: 3 is 1 standard deviation to the left of the mean.
P(3 < x < 4) = 0.34
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3 What is the chance that he works on a computer from 3 hours to 5 hours
Ans: 0.34 + 0.34 = 0.68
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4 What is the chance that he works on a computer more than 5 hours 
Ans: 5 hrs is 2 standard deviations above the mean.
P(x> 5) = 0.5000 - P(4 < x < 5)
= 0.5000 - -.34
= 0.16
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Cheers,
Stan H.