Statistics in a Modern World 800
Solutions to Exam 3

1.  
   1. (i) relative frequency
   2. 1 - .16 = .84
   3. .23 + .16 = .39
2. 1. Venn diagram should show two circles F and O; overlap has probability .05; in F but not O has probability .03; in O but not F has probability .20.
   2. .08 + .25 - .05 = .28, or from Venn .03 + .05 + .20 = .28
   3. NOT independent because .08 * .25 doesn't equal .05
3. 1. inadmissible because they sum to more than 1
   2. inadmissible because probabilities cannot exceed 1
   3. inadmissible because probabilities cannot be negative
   4. admissible; probabilities could be 2/3 and 1/3
   5. inadmissible because whether or not one wins must impact the probability of the other winning
4. (b) personal probability
5. 1/4 * 1/4 = 1/16
6. 1/4 * 1/3 = 1/12
7. 1(.1) + 2(.4) + 3(.3) + 4(.2) = 2.6
8. (a) more likely because more general
9. (d) representativeness
10. (c) equally likely
11. (b) gambler's fallacy
12. (b) availability (through media)
13. (e) optimism
14. (g) conservatism
15. (a) anchoring
16. (f) over-confidence
17. (b) because of reduction of risk to 0
18. (a) so many unusual events are possible that some are bound to happen occasionally
19. (a) 97% (solved in lecture)
20.  
    1. 1 - .02 = .98
    2. .02 * .9 = .018
    3. .98 * .05 = .049
    4. .018 + .049 = .067
    5. .018/.067 = .27
    6. (d) forgotten base rates

---

[ Home | Calendar | Assignments | Handouts ]