Question

In a survey, 20 people were asked how much they spent on their child's last birthday gift. The results were roughly bell-shaped with a mean of $38 and standard deviation of $3. Find the margin of error at a 98% confidence level. Give your answer to two decimal places.

Answer 1

Given that

sample size = n = 20

sample mean

sample Standard Deviation

Confidence level = C= 0.98

we want to calculate margin of error (E)

margin of error =

Degrees of freedom =n - 1 = 20 - 1 = 19

Critical value = tc=2.539 ..........(By using t table)

we get Margin of error = E = 1.70 ............(Answer)