1. A researcher is interested in studying if drinking coffee makes people more or less impulsive (he doesn't know which). He collects two samples of subjects (100 subjects each) from the same population, one that drinks coffee (group 1) and one that does not (group 2). He measures each on an impulsivity questionnaire, that ranges from 0 (not impulsive) to 100 (very impulsive). He finds that coffee drinkers have an impulsivity of 75, whereas non-coffee drinkers have an impulsivity of 67. He also calculates a standard error of the differences between groups (SE_M1-M2) of 4.08.

Calculate the test statistic (t-score) for this test (Two Independent Samples t-Test).

2.A teacher is interested if students learning from a new edition of a math textbook have higher or lower scores on a math test. She tests a sample of students, and finds the following scores (higher scores indicate better performance). She doesn't have scores for all of the students who used the old textbook, but she thinks that on average they score a "4", and so she decides to compare performance to this value. Here is the data she collects:

9

8

1

2

7

9

10

1

8

8

9

Calculate the test statistic (t-obtained) for this test (One-Sample t-Test)