6 pts Short answers We are to compare the effect of amount o

(6 pts) Short answers.

We are to compare the effect of amount of water taken on the weight of people. To test this, we had subjects of 20 people to have 5 oz. of water a day for 20 days. After that, we had the same subjects to have 50 oz. of water a day for 20 days. What type of test would be good for this purpose? Get the answer from the lecture or textbook.

We are comparing average income of two groups: plumber and carpenter. We want to test if the mean values of the two populations are the same. List two conditions for a z-test.

Solution

1) First we tested effect of amount of water taken for 20 people to have 5 oz of water for 20 days. After that, we had the same subjects to have 50 oz. of water a day for 20 days. This is the type of before and after type test. That is here we must use paired t test.

2) Here we use z test for comparing means of two independent groups.

Conditions are given below :

1) Sample must be independent and random.

2) The populations from which the samples drawn are normal.

3) Sample standard deviations must be known.