Quantitative Aptitude Ques 1535
Question: Out of 30 consecutive positive integers, two are chosen at random. Find the probability of their sum to be even.
Options:
A) $ \frac{14}{29} $
B) $ \frac{11}{29} $
C) $ \frac{17}{29} $
D) $ \frac{19}{29} $
Show Answer
Answer:
Correct Answer: A
Solution:
- (a) The total number of ways of choosing two out of 30, i.e. $ {}^{30}C _2 $ ways. Let E = Event of choosing two numbers such that their sum is even.
$ \therefore $ $ P(E)=\frac{n(E)}{n(S)}=\frac{{}^{15}C _2+{}^{15}C _2}{{}^{30}C _{12}} $ $ =\frac{105+105}{435}=\frac{210}{435}=\frac{14}{29} $