Probability Questions

Multiple choice
  1. The odds against are $5:11$
  2. The odds against are $11:5$
  3. The odds against are $16:5$
  4. The odds against are $5:16$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Total outcomes for 4 tosses are 2^4 = 16. Sums less than 15: (3,3,3,3)=12, (3,3,3,5)=14, (3,3,5,3)=14, (3,5,3,3)=14, (5,3,3,3)=14. There are 5 outcomes with sum < 15 and 11 outcomes with sum >= 15. The odds against are 11:5.

Multiple choice
  1. $32$
  2. $48$
  3. $20$
  4. $96$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Total ways to draw 3 balls from 6 (2 white, 4 red) is 6C3 = 20. Ways to draw 3 balls with no red (all white) is 2C3 = 0. Since there are only 2 white balls, it is impossible to draw 3 white balls. Thus, all combinations of 3 balls must contain at least one red ball. Total ways = 20.