1.

A bag contains 5 red balls and some of blue balls. If the probability of a drawing a blue ball is doubled that of a ref ball . Find the number of blue balls in the bag.

Answer»

Given that, a BAG CONTAINS 5 red balls and some BLUE balls.

Number of red balls = 5

Let us assume that the bag contains 'x' blue balls.

Therefore, the total number of balls = x + 5

Now,

Probability = (Number of favourable outcomes)/(Total number of outcomes)

For Red balls:

Number of favourable outcomes = 5

Total number of outcomes = x + 5

P(red balls) = 5/(x + 5)

For blue balls:

Number of favourable outcomes = x

Total number of outcomes = x + 5

P(red balls) = x/(x + 5)

Also given that, the probability of a drawing a blue BALL is doubled that of a ref ball.

According to question,

⇒ x/(x + 5) = 2 × [5/(x + 5)]

The denominator, throughout cancel. We left with

⇒ x = 2(5)

⇒ x = 10

Therefore,

There are 10 blue balls in the bag.


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