A recent report states that Canadians received an average tax return refund of $1600 last year with a standard deviation of $715. With recent tax changes implemented over the past year, you believe that the average tax return will change for the upcoming year. A random survey of 200 Canadians who have already filed their tax returns for this year is recorded and the sample mean was $1,723.

a) Construct a 95% confidence interval estimate for the average tax return for all Canadians for this year. Use σ= $715.

b) At this level of confidence does this sample provide enough evidence to suggest that the average tax return will be significantly different for the upcoming year than it was last year? Justify your answer.