Question

A three digit number is formed by using numbers $1,2,3$ and $4.$ The probability that the number is divisible by $3,$ is

• A. $2/3$
• B. $2/7$
• C. $1/2$
• D. $3/4$

Answer 1

The correct option is C $1/2$

No. of ways of formation of three digit number ${}^4{P}_3=24$

No. of $3$digit numbers that sum up to give $3$ multiples is ${}^4{C}_2=12$ ways

Arranging them is $\frac{12}{24}=\frac{1}{2}$