Benny has just finished collecting data to determine if risk level has a significant effect on recidivism. In order to test his hypothesis, he gathered a random sample of 36 high-risk offenders and a random sample of 42 low-risk offenders and compared them on the average number of re-arrests over 12 months. Benny hypothesizes that high-risk offenders have a significantly different average number of re-arrests than low-risk offenders. Use the following data to test his hypothesis.

High-risk Low-risk

_M1 = 4.3 M₂ = 3.1

s²₁ = 2.4 s²₂ = 3.0

1. Which test should Benny use to test his hypothesis?

a. Independent samples t test

b. Pearson's r

c. One sample t test

d. One sample z test

2. What is Benny's null hypothesis?

a. H₀: M =

b. H₀: M>

c. H₀:₁=₂

d. H₀:₁>₂

3. What is Benny's research hypothesis?

a. H₁: M_{1 <}M₂

b. H₁: M <

c. H₁:M

d. H₁: M₁ M₂

4. What is the obtained value of t (t_obt)?

a. 2.337

b. -8.540

c. 3.201

d. -1.294