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

A) 1/32
B) 1/16
C) 3/16
D) 5/16
Explanation

(d)
The probability of getting a number either 2 or 3 in one toss is $\frac{1}{2}$
Condition for getting the sum 12 in five tossed is (2, 2, 2, 3, 3).
$\therefore$ Required probability $= {\ ^{5}C}_{3}\left( \frac{1}{2} \right)^{3}\left( \frac{1}{2} \right)^{2}$
$= \frac{5 \times 4}{2 \times 1}\left( \frac{1}{2} \right)^{5}$
$= 10 \bullet \frac{1}{2^{5}} = \frac{5}{16}$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.