# A Jar Contains 54 Marbles, Each of Which Some Are Blue, Some Are Green and Some Are White. the Probability of Selecting a Blue Marble at Random is 1 3 and the Probability of Selecting a - Mathematics

Short Note
Sum

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

#### Solution

Total number of marbles = 54.

It is given that, 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 3 types of marbles in the jar, the sum of probabilities of all three marbles must be 1.

therefore 1/3 + 4/9 + x = 1

⇒ (3 +4)/9 + x  = 1

⇒ x = 1 - 7/9

⇒ x = 2/9

therefore P("getting a while marble")=2/9  ..........(1)

Let the number of while marbles be n.

Then, P(getting a while marble) =n/54 ........(2)

From (1) and (2),

n/54 = 2/9

rArr n = (2xx54)/9

⇒ n = 12

Thus, there are 12 white marbles in the jar.

Is there an error in this question or solution?

#### APPEARS IN

RS Aggarwal Secondary School Class 10 Maths
Chapter 15 Probability
Exercise 15B | Q 13 | Page 697