Confidence Interval Help!!!

Question

In a survey, 23 people were asked how much they spent on their child's last birthday gift. The results were roughly bell-shaped with a mean of $50 and standard deviation of $7. Construct a confidence interval at a 99% confidence level.

Give your answers to one decimal place.

Answer 1

CI = mean +/- t-critical * standard deviation/sqrt(sample size)

t-critical for 99% confidence interval is t-tail value for 0.005 and 22 DOF. = 2.819

mean = 50

standard deviation = 7

sample size = 23