Answers to the Review questions from Homework 2
Review Exercise Answers (Chapter 5)
4 (a) 20% (b) 12%. For part (a) (600 - 500 )/120 = .83 round it up to .85 and check the normal table. To get the 20% try (100 - 60.47) divided by 2 is 19.765 or about 20%. For part (b) calculate Z = (600 - 460) / 120 = 1.16 or about 1.20 and the percentage is (100 - 76.99) divided by 2 or 11.51%, about 12%6. The answer is no. The distribution of LSATs is not normal. We know from the characteristics of the normal curve that about 16% of the observations should be above one standard deviation. In this example, no observations are higher than one standard deviation.
Chapter 13
8a.On one roll, the chance of getting 3 or more spots is 4/6 (i.e. rolling a 3, 4, 5, 6 out of 6 possible choices). So the chance of getting 3 or more spots on 4 rolls is (4/6)4 or about 20%.8b. None of the rolls show 3 or more spots if all of the rolls show 2 spots or fewer (i.e. rolling a 1 or a 2 out of 6 possible choices). The chance is (2/6)4 or about 1.2%
8c. 100% - 20% = 80%
10. Box ii is better, there is more of a chance to get a 5 on a random selection. With box ii you will get around 50 1's and 50 5's, so you will earn about $300.