CBSE Class 10 Maths (Standard) 2015 · Paper 30/2/1 · Question 14

Probability 3 marks Medium

A bag contains

18

balls out of which

x

balls are red.

(i)If one ball is drawn at random from the bag, what is the probability that it is not red?
(ii)If $2$ more red balls are put in the bag, the probability of drawing a red ball will be $\frac{9}{8}$ times the probability of drawing a red ball in the first case. Find the value of $x$ .

(i)If one ball is drawn at random from the bag, what is the probability that it is not red?
(ii)If 2 more red balls are put in the bag, the probability of drawing a red ball will be $\frac{9}{8}$ times the probability of drawing a red ball in the first case. Find the value of $x$ .

Answer

(i)

P (not red) = \frac{18 - x}{18}

, which equals

\frac{10}{18} = \frac{5}{9}

for

x = 8

; (ii)

x = 8

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