Question

Question 1:

The General Social Survey has a survey question: “Would you be willing to pay much higher taxes in order to protect the environment?” To test whether there is a difference between this year’s “Yes” rate and last year’s “Yes” rate, a sample of 500 people this year (Group 1) and 500 people last year (Group 2) were selected. Assume α=0.05.

If the test statistic is 2.08, what is the p-value?

(a) 0.4812

(b) 0.5-0.4812

(c) (0.5-0.4812)*2

(d) (1-0.4812)*2

Question 2:

The probability that a student owns a car is 74%. The probability that a student owns a car or drives to school is 88%. The probability that a student owns a car and drives to school is 56%. Given that the student drives to school, what is the probability that the student owns a car?

(a) 70%

(b) 80%

(c) 76%

(d) 74%

Question 3:

A manager has kept track of the number of products sold per day. The chance that 10 products are sold is 12%. The change that 11 products are sold is 33%. The chance that 12 products are sold is 26%. The chance that 13 products are sold is 18%. Finally, the chance that 14 products are sold is 11%. What is the expected number of products sold per day?

(a) 11.03

(b) 13

(c) 11.83

(d) 12

Question 4:

Assume 90% of students will finish a test on time. There are 15 students taking a test. How likely is it that at least 13 students will finish the test on time?

(a) 26.7%

(b) 54.9%

(c) 81.6%

(d) 18.4%

Answer 1

Question 1)

Answer)

We need to use standard normal z table to estimate the p-value

Given test statistics = 2.08

From z table, P(z>2.08) = 0.0188

As the test is two tailed

P-value = 2*0.0188 = 0.0376

Or

(c) (0.5-0.4812)*2

As (0.5-0.4812)*2 = 0.0376

Question 2)

Answer)

Lets say we have a sample size of 100

74% owns a car = 74

Owns a car or drives to school = 88

Owns a car and drives to school = 56

P(a or b) = p(a) + p(b) - p(a and b)

So, 88 = drives to school + 74 - 56

Drives to school = 70

Probability is = favorable/total

Total = student drives to school = 70

Favorable = owns a car = 56

Probability = 56/70 = 80%