Question

Questions on the topic: two means independent sampling

1.Assume that σ21=σ22=σ2. Calculate the pooled estimator of σ2 when the first sample gives s21=125 and the second independent sample gives s22= 126, and n1=n2=25. Give your answer to two decimal places , do not round up or down.

2.
A company makes two types of paint. Independently a samples of paint from each type of paint was used and drying times recorded. Let D = [ ( sample average for sample one ) - ( sample average for sample two) ] .

The sample sizes were n1=17 and n2 = 12 .

We assumed that the two populations ( paint drying times for the two types of paint) have equal variances .

For the samples taken, D =2.1 and the pooled sample estimator of the common (equal ) population variance is (sp)2 =( 4.0)(4.0) .

Construct a 95% confidence interval estimate for the difference in the two population means (type 1 paint versus type 2 paint) or
μ1−μ2
.

For your answer give the width of your confidence interval , to two decimal places , do not round up or down.

Answer 1

Money wasted!

Answer 2

I am so sorry they missed you D:. If you want, i can return your money :D