Quantitative Aptitude Ques 38

Question: Five coins whose faces are marked 2, 3 are tossed. The chance of obtaining a total of 12 is

Options:

A) $ \frac{1}{32} $

B) $ \frac{1}{16} $

C) $ \frac{3}{16} $

D) $ \frac{5}{16} $

Show Answer

Answer:

Correct Answer: C

Solution:

  • The probability of getting a number either 2 or 3 in one toss is $ \frac{1}{2}. $ Condition for getting the sum of 12 in five tosses is (2, 2, 2, 3, 3).

$ \therefore $ Required probability $ ={}^{5}C _3{{( \frac{1}{2} )}^{3}}{{( \frac{1}{2} )}^{2}} $ $ =\frac{5\times 4}{2\times 1}{{( \frac{1}{2} )}^{5}} $ $ =10.\frac{1}{2^{5}}=\frac{5}{16} $