Easy Probability Solved QuestionAptitude Discussion

 Q. A five-digit number is formed by using digits 1, 2, 3, 4 and 5 without repetition. What is the probability that the number is divisible by 4?
 ✔ A. 1/5 ✖ B. 5/6 ✖ C. 4/5 ✖ D. None of these

Solution:
Option(A) is correct

A number divisible by 4 formed using the digits 1, 2, 3, 4 and 5 has to have the last two digits 12 or 24 or 32 or 52.

In each of these cases, the five digits number can be formed using the remaining 3 digits in $3! = 6$ ways.

A number divisible by 4 can be formed in $6×4 = 24$ ways.

Total number that can be formed using the digits 1, 2, 3, 4 and 5 without repetition

$= 5! = 120$

Required probability,

$= 24/120$

$= \textbf{1/5}$

(1) Comment(s)

S Malik
()

any one please explain it with another method...