1) Marley drives to work every day and passes two independently operated traffic lights. The probability that both lights are red is 0.35. The probability that the first light is red is 0.48. What is the probability that the second light is red, given that the first light is red?

a) 0.13

b) 0.35

c) 0.48

d) 0.73

2) In a study of 250 adults, the average heart rate was 70 beats per minute. Assume the population of heart rates is known to be approximately normal,

with a standard deviation of 12 beats per minute. What does a margin of error of 2 for the 98% confidence interval of the average beats per minute mean?

a) There is a 1% chance that the population mean is less than 70 beats per minute.

b) There is a 1% chance that the population mean is more than 70 beats per minute. c) There is a 99% chance that the population mean is between 58 and 82 beats per minute.

d) There is a 99% chance that the population mean is between 68 and 72 beats per minute.

3) Arlene is testing whether school is more enjoyable when students are making high grades. She asked 100 students if they enjoyed school and whether their GPA was above or below 3.0. She found that 30 of the 40 students with a GPA above 3.0 reported that they enjoyed school, and 15 of the 60 students with a GPA below 3.0 reported that they enjoyed school. What is the probability that a student with a GPA below 3.0 does not enjoy school?

a) 15%

b) 25%

c) 45%

d) 75%