Probability Interval, statistics help

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Probability Interval, statistics help!

Homework Statement

Assume that the population is normal with mean of 90 and standard deviation of 25. A sample of size 100 will be selected.
a.) What is your best estimate for the value of the sample mean?
b.) What is the value of the standard error?
c.) In the 95% probability interval for the sample mean, what is the value of the margin of error?
d.) Construct the 95% center probability interval for the sample mean. (Give lower limit (LL) and upper limit (UL).

Homework Equations

(work shown below)

The Attempt at a Solution

4a.) 90
4b.) 25 / (100)^1/2 = 25/10 = 5/2
4c.) 1.96 * (5/2) = 4.9
4d.) LL= 90 – 4.9 = 85.1
UL= 90 + 4.9 = 94.9
(84.1, 94.9)

Homework Statement

Homework Equations

The Attempt at a Solution

 

[Valkarie]

a.) What is your best estimate for the value of the sample mean?Answer: 90b.) What is the value of the standard error?Answer: 25/√100 = 25/10 = 5/2 c.) In the 95% probability interval for the sample mean, what is the value of the margin of error?Answer: 1.96 * (5/2) = 4.9d.) Construct the 95% center probability interval for the sample mean. (Give lower limit (LL) and upper limit (UL).Answer: LL = 90 – 4.9 = 85.1UL = 90 + 4.9 = 94.9Interval: (85.1, 94.9)