Suppose that we have disjoint normal populations A and B with unknown population variances. Suppose we have a sample of size 10 from from population A and a sample of size 15 from population B which we would like to pool to form the pooled variance. But, for this we need to assume that the population variances are equal. If the sample variance for the sample from population A is 11 and the sample variance for the sample from population B is 7, then does our data actually give evidence that the two population variances are actually different? Give the P-Value of this data as evidence that the two population variances are different (use stattrek.org).

We are running a hypothesis test to see if blood pressure of African zebras differs significantly from Arabian horses.  We assume blood pressure in both populations is normally distributed and both populations have the same population variance in blood pressure which is unknown to us, so we use the sample variances to estimate the standard error for our calculations.  We have a sample of size 9 for the African zebras with mean 180 and a sample of size 16 for the Arabian horses with mean 190.  If the pooled variance is 36, then what is the standard error estimate for the estimator of the true mean difference in weight for the two populations? 15 NONE OF THE OTHERS 1.25 1.57 2.5

One sample has M = 18 and a second sample has M = 14. If the pooled variance for the two samples is 16, what is the value of Cohen’s d?

One sample has n=7 and SS=35 and a second sample has n =17 and SS =45. What is the pooled variance for these two samples?