Question

Find the 99% confidence interval for estimating μ_d based on these paired data and assuming normality. (Give your answers correct to one decimal place.)

Before	42	65	52	57	58	48
After	30	43	48	32	30	50

Lower Limit
Upper Limit

Answer 1

Before	After	Difference
42	30	12
65	43	22
52	48	4
57	32	25
58	30	28
48	50	-2

Sample mean if the difference, x̅_d =   14.8333
Sample standard deviation of the difference, s_d =   12.1395
Sample size,    n =   6

99% Confidence interval for the differnce:                                  

At α = 0.01, and df = 5, two tailed critical value, t-crit = T.INV.2T(0.05 , 5 ) =   4.032

Lower Bound  = x̅_d - t-crit*s_d/√n  = -5.1   

Upper Bound = x̅_d + t-crit*s_d/√n = 34.8