Confidence Interval Estimation

[urgas1]

Can anyone help me with this problem? Thank you very much!


2. A well known children's shoe store wants to estimate the mean retail value of
rain boots that it has in its inventory. A random sample of 20 rain boots
indicates an average value of $25.59 and a standard deviation of $ 4.25.

a. Assuming a normal distribution, set up a 95% confidence interval estimate
of the mean value of all rain boots in the store's inventory.

b. How can the results you obtained above help the store owner estimate the
total value of his inventory?

 

[Unco]

G'day,

x-bar - sigma/(sqrt(n)) < Mu < x-bar + sigma/(sqrt(n))

A random sample of 20 rain boots <-> n = 20

... had an average value of 25.59 <-> x-bar = 25.59

... and a SD of 4.25 <-> sigma = 4.25 (we assume the standard deviation of the sample is that of the population)

Plug 'n' chug!

For b, he could estimate the total value of his rain boots if he knows his expectation algebra. He could apply the same method to other inventory.