Question

n1   13   n2   9
x1bar   141   x2bar   161
s1   13   s2   12

Use this data to find the 98%98% confidence interval for the true difference between the population means. Assume that the population variances are equal and that the two populations are normally distributed.

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Step 1 of 3:

Find the critical value that should be used in constructing the confidence interval. Round your answer to three decimal places.

Step 2 of 3:

Find the standard error of the sampling distribution to be used in constructing the confidence interval. Round your answer to the nearest whole number.

Step 3 of 3:

Construct the 98%98% confidence interval. Round your answers to the nearest whole number.

Answer 1

Mean1 = 141

Sample size1 (n1) = 13

Standard deviation1 (s1) = 13

Mean2 = 161

Sample size2 (n2) = 9

Standard deviation2 (s2) = 12

1)

Confidence interval(in %) = 98

t_{\alpha/2, n_1 + n_2 -2} = 2.528

2)

3)

Since we know that

Required confidence interval = (-20.0-13.8227, -20.0+13.8227)

Required confidence interval = (-34, -6)

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