Question

A jar contains 54 marbles each of which is blue, green or white. The probability of selecting a blue marble at random from the jar is `1/3,` and the probability of selecting a green marble at random is `4/9dot` How many white marbles does the jar contain?

Answer 1

Correct Answer - 12
Total number of marbles in the jar= 54.
P(getting a blue marble) = ` 1/3` and P(getting a green marble) =` 4/9`.
Let P(getting a white marble) be x.
Since there are only three given types of marbles in the jar, we have
` 1/3+4/9 + x = 1 rArr 7/9 + x = 1 -7/9 = 2/9`.
` :. ` P(getting a white marble) = `2/9`.
Let the number of white marbles be n.
Then, P(getting a white marble) = ` n/54`.
` :. n/54 = 2/9 rArr 9n = 108 rArr n = 12`.
Hecne, there are 12 white marbles in the jar.