Multiple choice

An urn contains 11 balls numbered from 1 to 11. If a ball is selected at random, what is the probabiloity of having a ball with a number which is mutliple of either 2 or 3 ?

  1. $\displaystyle \frac{7}{11}.$
  2. $\displaystyle \frac{8}{11}.$
  3. $\displaystyle \frac{4}{11}.$
  4. $\displaystyle \frac{6}{11}.$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The multiples of 2 or 3 from 1 through 11 are 2, 3, 4, 6, 8, 9, and 10, giving seven favorable outcomes. The probability is therefore 7/11.

AI explanation

The total number of balls in the urn is 11. The multiples of 2 between 1 and 11 are 2, 4, 6, 8 and 10, and the multiples of 3 are 3, 6 and 9. Combining these gives the unique favorable numbers as 2, 3, 4, 6, 8, 9 and 10, which totals 7 numbers. Using the classical definition of probability, the required probability is the 7 favorable outcomes divided by the 11 total outcomes, which is 7/11.

Keep practicing — related questions