Probability Ques 30
Question-
A box contains few balls coloured with white, blue and green. The probability of choosing a white ball is $\frac{4}{15}$ and the probability of choosing a green ball is $\frac{2}{15}$. There are 10 blue balls. Suppose, the balls are numbered $1,2, \ldots$ up to number of balls in the box, what is the probability of choosing a ball containing a multiple of 2 or 3 ?
(1) $\frac{4}{5}$
(2) $\frac{1}{2}$
(3) $\frac{2}{3}$
(4) $\frac{3}{5}$
(5) $\frac{1}{4}$
(IBPS Bank PO/MT CWE (Main Exam) 18.11.2018)
Show Answer
Correct Answer: (3)
Solution: (3)
There are 30 balls in the box as probability of choosing 1 blue ball $=\frac{1}{3}$
Multiples of 2 up to 30 $=\frac{30}{2}=15$
Multiples of 3 up to 30 $=\frac{30}{3}=10$
Multiples of $6(2 \times 3)$ up to 30 $=\frac{30}{6}=5$
So, total such numbers are $=15+10-5=20$
So, required probability $=\frac{20}{30}=\frac{2}{3}$
BETA
