Question

The following results are for independent random samples taken from two populations.

Sample 1	Sample 2
n1 = 20	n2 = 30
x1 = 22.8	x2 = 20.1
s1 = 2.6	s2 = 4.6

(a)

What is the point estimate of the difference between the two population means? (Use

x₁ − x₂.

)

(b)

What is the degrees of freedom for the t distribution? (Round your answer down to the nearest integer.)

(c)

At 95% confidence, what is the margin of error? (Round your answer to one decimal place.)

(d)

What is the 95% confidence interval for the difference between the two population means? (Use

x₁ − x₂.

Round your answers to one decimal place.)

to

Answer 1

(A) The point estimate of   is   22.8-20.1=2.7

(B) For unequal variace DF : 47

(C) 2.0522

Standard error of difference is   

criticat value of t  

(D) 95% Confidence Interval for the Difference ( 0.644 , 4.756 )
Confidence Interval of     is   = 2.7 ± (2.01 * 1.0214) = 2.7 ± 2.0522