Standard deviation?

Customers experiencing technical difficulty with their internet cable hookup may call an 800 number for technical support. It takes the technician between 90 seconds and 14 minutes to resolve the problem. The distribution of this support time follows the uniform distribution.

What are the values for a and b in minutes?
a. 1.5
b. 14.

what is the mean time to resolve the problem. 6.25

what is the standard deviation of the time....???
What percent of problems take more than 5 minutes to resolve?


did I get the right answers for the first 2 questions? How do I figure the others?

Ainsworth said:

Customers experiencing technical difficulty with their internet cable hookup may call an 800 number for technical support. It takes the technician between 90 seconds and 14 minutes to resolve the problem. The distribution of this support time follows the uniform distribution.

What are the values for a and b in minutes?
a. 1.5
b. 14.

what is the mean time to resolve the problem. 6.25

what is the standard deviation of the time....???
What percent of problems take more than 5 minutes to resolve?


did I get the right answers for the first 2 questions? How do I figure the others?

Click to expand...

First of all you need to give us the complete problem. For example, what you mean by between 90 sec and 14 min. Is that one standard deviation from the mean or what? Certainly it can't be the minimum and maximum as the uniform distribution does not end abruptly.

I'm not sure what formula you are using that requires the a and b but possible it is something like, if a and b are each one standard deviation from the mean in a normal deviation then the mean is (some formula involving a and b) and the standard deviation is (another formula involving a and b). If that is the case, then I think you used the wrong formula because, if the a and b were as given (which means you got the first question right), then 6.25 is the standard deviation not the mean.

Thank you!

Thank you