Question

A random sample of 33 taxpayers claimed an average of ​$9,668 in medical expenses for the year. Assume the population standard deviation for these deductions was ​$2,415.

Construct confidence intervals to estimate the average deduction for the population with the levels of significance shown below.

a.	1 %
b.	5 %
c.	20 %

a. The confidence interval with a 1 % level of significance has a lower limit of $ and an upper limit of ​$

Answer 1

a)

confidence interval with a 1 % level of significance has a lower limit of 8585 and an upper limit of 10751

( please try 8583 to 10753 if above comes wrong due to rounding and revert)

b)

for 95 % CI value of z=				1.960
margin of error E=z*std error                            =				823.979
lower confidence bound=sample mean-margin of error=				8844.02
Upper confidence bound=sample mean +margin of error=				10491.98

confidence interval with a 5 % level of significance has a lower limit of 8844 and an upper limit of 10492

c)

for 80 % CI value of z=				1.280
margin of error E=z*std error                            =				538.109
lower confidence bound=sample mean-margin of error=				9129.89
Upper confidence bound=sample mean +margin of error=				10206.11

confidence interval with a 20% level of significance has a lower limit of 9130 and an upper limit of 10206

( please try 9129 to 10207 if above comes wrong due to rounding and revert)