Probability Ques 21
Question-
A bag contains 2 red balls, 5 yellow balls and ’ $x$ ’ green balls. One ball is drawn at random and the probability of ball being yellow is $\frac{5}{9}$. What is the value of $x$ ?
(1) 3
(2) 12
(3) Other than those given as options
(4) 6
(5) 2
(IBPS RRBs Officer CWE (Prelim Exam) 16.09.2017)
Show Answer
Correct Answer: (5)
Solution: (5)
Total number of balls in the bag $=7+x$
Total possible outcomes $={ }^{(7+x)} C_{1}=7+x$
Total favourable outcomes $={ }^{5} C_{1}=5$
$\therefore$ Required probability $=\frac{5}{7+x}$
$\therefore \frac{5}{7+x}=\frac{5}{9}$
$\Rightarrow 7+x=9$
$\Rightarrow x=2$
BETA
