Question

Before bidding on a contract, a contractor, wants to be 95% confident that they are in error by at most 5 minutes in using the mean of a random sample to estimate the average time it takes a certain kind of adobe brick to harden.

a)How large a sample is needed if they can assume σ=24 minutes for such bricks?

b)Why do we use the word confident here instead of probability?

c)Redo a) replacing “less than 5 minutes” for “at most 5 minutes”

Answer 1

b.

There is really no difference between the two words. It is just that the proper frequentist use of the word probability becomes awkward, and people have decided to use confidence instead.

c.

There is no change in answer. it is similar to (a)