Question

In a survey, 19 people were asked how much they spent on their child's last birthday gift. The results were roughly bell-shaped with a mean of $32 and standard deviation of $4. Find the margin of error at a 98% confidence level.

Answer 1

Formula for margin of error in Confidence Interval for Population mean when population Standard deviation is not known

Given,

Given
Sample Mean : : Sample mean of amount spent on their child's last birthday gift	32
Sample Standard Deviation : s : Sample standard deviation of amount spent on their child's last birthday gift	4
Sample Size : n: Number of people surveyed	19
Degrees of freedom : n-1	18
Confidence Level :	98
=(100-98)100	0.02
/2	0.01
	2.5524

the margin of error at a 98% confidence level

the margin of error at a 98% confidence level = 2.3422