Question

In a class of 40 statistics majors, each one constructs a 90% confidence interval for the unknown probability p of a weighted coin landing heads. About how many of the 40 intervals will capture the value of the unknown parameter p? About how many will miss it?

Answer 1

36 intervals will capture the value of the unknown parameter p, and 4 will miss it.

Explanation:

x% confidence interval:

A confidence interval is built from a sample, has bounds a and b, and has a confidence level of x%. It means that we are x% confident that the population mean is between a and b. x% of confidence intervals capture the unknown parameter.

About how many of the 40 intervals will capture the value of the unknown parameter p?

90% of them will capture, so:

0.9*40 = 36

0.1*40 = 4

36 intervals will capture the value of the unknown parameter p, and 4 will miss it.