Probability Questions

Multiple choice
  1. $\displaystyle \frac{25}{216}$
  2. $\displaystyle \frac{25}{36}$
  3. $\displaystyle \frac{5}{36}$
  4. $\displaystyle \frac{125}{216}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

For X = 3, the first two rolls must not be 6 (probability 5/6 each) and the third must be 6 (probability 1/6). P(X=3) = (5/6) * (5/6) * (1/6) = 25 / 216.

Multiple choice
  1. $\displaystyle \frac{1}{52}$
  2. $\displaystyle \frac{1}{26}$
  3. $\displaystyle \frac{103}{2704}$
  4. $\displaystyle \frac{824}{2704}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Probability of NOT getting Ace of hearts in one draw is 51/52. Probability of NOT getting it in two draws is (51/52) * (51/52) = 2601/2704. Probability of at least one Ace of hearts = 1 - 2601/2704 = 103/2704.

Multiple choice
  1. $\displaystyle \frac{6}{20}$
  2. $\displaystyle \frac{7}{20}$
  3. $\displaystyle \frac{8}{20}$
  4. $\displaystyle \frac{9}{20}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Numbers divisible by 3 are {3, 6, 9, 12, 15, 18} (6 numbers). Numbers divisible by 5 are {5, 10, 15, 20} (4 numbers). The number 15 is counted in both, so the unique numbers are {3, 5, 6, 9, 10, 12, 15, 18, 20}, which is 9 total. The probability is 9/20.