Question

Can someone please help me? I've been trying to figure this out for days. I don't understand how to construct a confidence interval.

I know that the red box has a mean value of 15.11 and the blue box's mean is 16.83. The difference of sample means is 1.74. The red standard deviation is 3.868 and the blue one is 2.933. the standard deviation of the sample mean differences is 0.69. How do I use all this to construct the interval with no difference between the population means.

Answer 1

Explanation:

Confidence interval is:

CI = x ± CV · SE

where x is the mean, CV is the critical value, and SE is the standard error.

There is no difference between the population means, so x = 0.

The confidence level is 95%, so CV = 1.96.

SE = 0.69.

So the confidence interval is:

CI = 0 ± (1.96) (0.69)

CI = (-1.35, 1.35)

1.74 is outside of the confidence interval, so it is statistically significant.