Multiple choice

A bag contains five yellow balls and some white balls If the probability of picking a white ball is twice that of picking a yellow ball how many white balls are there?

  1. 20

  2. 10

  3. 16

  4. 18
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let w be the number of white balls. Total balls = 5 + w. P(white) = w / (5 + w). P(yellow) = 5 / (5 + w). Given P(white) = 2 * P(yellow), so w / (5 + w) = 2 * (5 / (5 + w)). Thus w = 10.

AI explanation

Let the number of white balls be x, making the total number of balls 5 + x. The probability of picking a white ball is x / (5 + x) and the probability of picking a yellow ball is 5 / (5 + x). Setting x / (5 + x) = 2 * (5 / (5 + x)) gives x = 10. Therefore, there are 10 white balls in the bag.

Keep practicing — related questions