Probability Questions

Multiple choice
  1. $\displaystyle \frac{2}{9}$
  2. $\displaystyle \frac{5}{9}$
  3. $\displaystyle \frac{8}{9}$
  4. $\displaystyle \frac{8}{13}$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Initially there are 10 balls (6 white, 4 black). If one white ball is removed, 9 balls remain, 5 of which are white. The probability of drawing a white ball next is 5/9.

Multiple choice
  1. $\displaystyle \frac{7}{26}$
  2. $\displaystyle \frac{1}{4}$
  3. $\displaystyle \frac{3}{13}$
  4. $\displaystyle \frac{15}{52}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Primes between 1 and 52: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47. There are 15 primes. Probability = 15/52.

Multiple choice
  1. $\dfrac{1}{4}$.
  2. $\dfrac{7}{12}$.
  3. $\dfrac{5}{12}$.
  4. $\dfrac{11}{12}$.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The total outcomes when rolling two dice is 36. The outcomes that sum to 11 or 12 are (5,6), (6,5), and (6,6), which are 3 outcomes. The probability of getting 11 or 12 is 3/36 = 1/12, so the probability of getting 10 or lower is 1 - 1/12 = 11/12.