In a survey, 24 people were asked how much $ spent on their child's birthday gift. The results were bell-shaped with a mean of $35.9 and standard deviation of $13.3.

Question

Estimate how much a typical parent would spend on their child's birthday gift (use a 99% confidence level). Give your answers to 3 decimal places. 

Express your answer in the format of x¯ ±  E. 

$ ± $

Answer 1

Hello, thank you for taking the time to post your question!

The relevant variables here are

n = 24

x-bar = 35.9

s = 13.3

confidence level of 99%, meaning t* is 2.807

that makes the confidence interval

35.9 +/- (2.807 * 13.3 / sqrt(24))

=35.9 +/- 7.62

That means that the lower bound is $28.20 and the upper bound is $43.52.

I hope that helps get you moving in the right direction! Feel free to message me if you have any more questions beyond that about this concept :)