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Two random samples are selected from two independent populations. A summary of the samples sizes, sample...

Two random samples are selected from two independent populations. A summary of the samples sizes, sample means, and sample standard deviations is given below:

n1=39,n2=40,x¯1=50.3,x¯2=73.8,s1=6s2=6.1

Find a 98% confidence interval for the difference μ1−μ2 of the population means, assuming equal population variances.

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Answer #1

Here  .

The degrees of freedom is .

We use pooled variance since the population variances are assumed equal.

The pooled sample variance is

The confidence interval for for true difference in means

The 98% confidence interval for true difference in means

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