Probability Questions 1B

11. A couple has 3 children. What is the probability there are exactly two girls among them.
a. 3/8 b. 1/ 2 c. 7/8 d. 5/8

12. Same setup. What is the probability of at most 2 girls.
a. 3/8 b. 1/ 2 c. 7/8 5/8

13. If a restaurant offers 3 different appetizers, 5 entrees (main dishes), 4 desserts, and 6 drinks, how many possibilities are there if a person chooses something from each of the categories?
a. 18 b. 4 c. 360 d. 46

14. If an urn contains 20 numbered balls from 1 to 20 and you pick one, what is the probability the ball you pick has a number divisible by 3?
a. .2 b. .3 c. 1/3 d. .25

15. It's known that Linda has a Ph.D. in physics and was president of her class. Given this, what is more probable: Is it X - Linda works as a teller in a bank or is it Y - Linda works as a teller in a bank and is active in feminist causes?
a. X, more probable b. Y, more probable c. equally probable d. not enough info

16. What is the probability of rolling a pair of dice and getting 4 straight 8's?
a. 4*(5/36) b. 1 - (5/36)4 c. (8/36)4 d. (5/36)4

17. If a die is biased and there is a 15% chance that it lands on any of the numbers from 1 to 5, then what is the probability the die will land on 6?
a. 16.6% b. 15% c. 20% d. 25%

18. Which would likely have the smallest standard deviation?
a. the times it takes to drive along the same 15-mile route every week day at 9 AM
b. the times it takes to drive along the same 15-mile route every week day at 9 PM
b. the times it takes to do the same drive at random times during the week
c. the times it takes to walk one block to the convenience store at 9 PM

19. If 75% of the students achieve scores greater than 80, but 25% get aa 0 on the test, then
a. the median is greater than 80 and is greater than the mean
b. the median is about 40
c. the mean is greater than the median
d. not enough information to tell.

20. A roulette wheel (36 red, 36 black, 2 green sectors) is spun. What is the probability the wheel doesn't land on red?
a. 47.3% b. 50% c. 52,6% d. 5.3%