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July 23, 2014

July 23, 2014

Posted by **Shelby** on Sunday, October 27, 2013 at 9:30pm.

has a 250-gigabyte hard drive. The university wants to estimate the space

occupied on the hard drives. A random sample of 100 computers showed a mean

of 115 gigabytes used with a standard deviation of 20 gigabytes.

-I'm not clear on how to calculate these answers and would appreciate help a great deal. Thank you!

a) What is the standard error of the mean?

b) What is the probability that a sample mean is greater than 200 gigabytes?

c) What is the probability that a sample mean is greater than 120 gigabytes?

d) What is the probability that a sample mean is between 111 and 119

gigabytes?

- Statistics -
**Kuai**, Sunday, October 27, 2013 at 10:29pmA. The standard error of the mean = 20/sqrt([100]) = 2

answer 2

B. z =(200-115)/(20/sqrt((100))

z = 42.5

answer 0

C. z = (120-115)/2 = 2.5

answer 0. 9938

D. z = (111-115) /2

z = -2

z = (119-115)/2

z = 2

.9772-.0228 = 0.9544

Answer 0.9544

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