For Batch A, a random sample of 20 skewers were found to have an average length of 21.6 cm.

For Batch B, 10 random skewers  gave an average length of 20.4 cm.

The standard error in the difference was found to be 0.766 cm.

Calculate the 90% Confidence interval on the difference in length between the two batches (A-B).

Assume that the lengths are normally distributed, do not assume the population variances are equal, and use the conservative "by hand" estimate for the degrees of freedom (ie lesser n-1).

In comparing a breakup and a surface count of the number of choc chips in a cookie, a researcher takes four cookies of one type and records the following data:

Find the mean of the difference (breakup count - surface count), correct to two decimal places.

Suppose that a difference between two groups is examined.

In testing the hypotheses H₀:mu=10 against H_A:mu not =10,

a sample of size 16 was used and gave a standardized score for the sample (a t-statistic) of 1.30.

The associated P-value

A one-sample Z-test with a 1-tailed alternative hypothesis was carried out.

A z-statistic of -1.32 has been calculated for the sample mean.

An hypothesis test had hypotheses:  H₀:µ = 10 against H_A:µ  not = 10  at a level of significance of 0.05.

A 95% confidence interval for the mean was calculated to be (9.61, 9.93).

Which of the following conclusion is the best for this situation?