Need help on this !!

Question

In a survey, 12 people were asked how much they spent on their child's last birthday gift. The results were roughly bell-shaped with a mean of $36 and standard deviation of $9. Find the margin of error at a 98% confidence level.

Answer 1

margin of error = t-value * standard deviation / square root of sample size

= 2.718* 9 / sqrt(12)

= 7.062

Find t-value by matching area (1-.98)/2 = .01 with degree of freedom 11 in a t-chart.