Probability Questions

Multiple choice
  1. $\dfrac{1}{64}$
  2. $\dfrac{1}{32}$
  3. $\dfrac{1}{16}$
  4. $\dfrac{1}{8}$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Binomial probability P(X=k) = nCk * (1/2)^n. P(X=3) = P(X=5) implies nC3 = nC5. This means 3+5 = n, so n=8. Probability of one head = 8C1 * (1/2)^8 = 8 / 256 = 1/32.

Multiple choice
  1. $\dfrac{6}{4165}$
  2. $\dfrac{23}{4165}$
  3. $\dfrac{1797}{4165}$
  4. $\dfrac{1}{4165}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Total ways to choose 5 cards = 52C5 = 2598960. Ways to get a full house (3 of one kind, 2 of another): Choose the rank for the triple (13C1), choose 3 suits (4C3), choose the rank for the pair (12C1), choose 2 suits (4C2). Total = 13 * 4 * 12 * 6 = 3744. Probability = 3744 / 2598960 = 6 / 4165.

Multiple choice
  1. $\dfrac {40}{143}$
  2. $\dfrac {70}{143}$
  3. $\dfrac {3}{13}$
  4. $\dfrac {10}{13}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Total balls = 13. Total ways to draw 3 balls = 13C3 = (13*12*11)/(3*2*1) = 286. Ways to draw only red = 8C3 = 56. Ways to draw only white = 5C3 = 10. Ways to draw both colors = Total - (only red + only white) = 286 - (56 + 10) = 220. Probability = 220/286 = 110/143 = 10/13.

Multiple choice
  1. $\displaystyle \frac{91}{216}$
  2. $\displaystyle \frac{108}{216}$
  3. $\displaystyle \frac{125}{216}$
  4. $\displaystyle \frac{127}{216}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The probability that D4 does NOT show a number appearing on D1, D2, or D3 is (5/6)^3 = 125/216. The probability that it DOES show a number appearing on one of the others is 1 - 125/216 = 91/216.