You think people who get tattoos will make less money than people who don't have tattoos. You ask 39 people with tattoos and 43 people without tattoos how much money they made last week. The group with tattoos had an average income of $806 (standard deviation = $194) and the group without tattoos had an average income of $891 (standard deviation = $165). You assume an alpha () of .05

a. What is the null hypothesis? What is the research hypothesis? Should you conduct a one- or a two-tailed test? Why?

b. Calculate the t-test, using .05 for alpha. Show your work and provide the t-statistic, t-critical, as well as the degrees of freedom (df).

c. What do you conclude?

2. A survey asks, "How safe do you feel about taking the COVID-19 vaccine?" Responses were measured on a 5-point scale: 1 = not at all, 2 = not very safe, 3 = somewhat safe, 4 = very safe, and 5 = completely safe. Those with a high school degree had an average score of 3.05 (s = 1.21, N = 32) while respondents with a bachelor's degree had an average score of 3.75 (s = 1.05, N = 30).

a. Calculate the one-tailed test (college graduates are more likely to feel safe); using (alpha) = .05. Show your work and provide the t-statistic, t-critical, as well as the degrees of freedom (df).

b. What do you conclude about the difference in attitudes between high school and bachelor's degree graduates? If you conducted a two-tailed test with = .05, would your decision have been different?