# CBSE Class 10-Mathematics: Chapter –15 Probability Part 15

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Question 6:

A bag contains 5 red balls, 4 green balls and 7 white balls. A ball is drawn at random from the box. Find the probability that the ball drown is

(a) white

(b) neither red nor white

Total number of balls in the bag

Total number of possible outcomes

(a) Favourable outcomes for a white ball

Required probability

(b) Favourable outcomes for neither red nor white ball=Number of green balls =4

Required probability

Question 7:

A box contains balls bearing numbers . A ball is drawn at random from the box, what is the probability that the number on the ball is

(i) An odd number

(ii) Divisible by 2 or 3

(iii) Prime number

Total number of outcomes (i) Favorable outcomes are i.e., 10 in number.

Required probability

(ii) Number “divisible by 2” are i.e., in number

Numbers “divisible by are i.e., in number

Numbers “divisible by or 3 are i.e., in number.

Numbers divisible by

Favourable outcomes

Required probability

(iii) Prime numbers are i.e., in number

Favourable outcomes =

Required probability

Question 8:

A bag contains red and some blue balls,

(i) if probability of drawing a blue ball from the bag is twice that of a red ball,find the number of blue balls in the bag.

(ii) if probability of drawing a blue ball from the bag is four times that of a red ball,find the number of blue balls in the bag.

Let number of blue balls

Total number of balls

Probability of red ball

Probability of blue ball

By given condition,

(i)

No. of blue balls

(ii) Here,

Hence, number of blue balls

Question 9:

A box contains 3 blue marbles, 2 white marbles. If a marble is taken out at random from the box, what is the probability that it will be a white one? Blue one? Red one?

Total no. of possible outcomes

No. of favourable outcomes for white marbles

Required probability

No. of favourable outcomes for blue marbles

Required probability

No. of favourable outcomes for red marbles

Required probability