Statistics help? 10 pts
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Statistics help? 10 pts

[From: ] [author: ] [Date: 12-04-04] [Hit: ]
Thanks.(5.75 - 7) / 1 = -1.go to the z chart and find where z=-1.p=0.that is p for z-1.......
I really need help with this problem I cannot figure it out.

A survey was conducted to measure the number of hours per day that adults in the US spend on computers. In the survey, the number of hours were normally distributed, with a mean of 7 hours and a standard deviation of 1 hour. If 45 adults in the US are randomly selected, how many would you expect to say they spend more than 5.75 hours a week on the computer?

the answer that I got is 4.752

I was just wondering if this is correct because the only other problem in the book says less than not more than.

Thanks.

-
normalize the number

(5.75 - 7) / 1 = -1.25

go to the z chart and find where z=-1.25

p=0.1056

that is p for z<-1.25 but you want z>-1.25 so just take 1-p

p = 1-0.1056 = 0.8944

there are 45 adults so the number of adults would be

45(p) = 45(0.8944) = 40.25 adults
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