A golf instructor is interested in determining if her new technique for improving players' golf scores is effective. She

takes four new students. She records their 18-hole scores before learning the technique and then after having taken her class.

She conducts a hypothesis test. The data are as follows.

Player 1 Player 2 Player 3 Player 4

Mean score before class 83 78 93 87

Mean score after class 80 80 86 86

Sample Size Mean Std Dev

Before Instruction 4 85.25 6.34

After Instruction 4 83 3.46

Difference 4 2.25 3.77

I'm having trouble figuring out how the std dev difference is calculated? Where is this number coming from?

What is the null and alternative hypothesis?

2. What is the test statistic?

3. How many degrees of freedom are needed to set critical t?

4. If critical t = 4.51 (you decide: +, -, +/1) what is your test decision?

5. Did golf scores significantly improve?