Q. A five digits number is formed by writing the digits 1, 2, 3, 4, 5 in a random order without repetitions. Then the probability that the number is divisible by 4, is
A) $\frac{3}{5}$
B) $\frac{18}{5}$
C) $\frac{1}{5}$
D) $\frac{6}{5}$
Explanation
(c)
Total number of ways to from the numbers of five digits with 1, 2, 3, 4, 5 are $= 5! = n\ (S)$
Total number of numbers which are divisible by 4
$n(E) = 3! \times 4 = 4!$
$\therefore$ Required probability $= \frac{n(E)}{n(S)} = \frac{4!}{5!} = \frac{1}{5}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.