If a 4 digit number is formed with digits 1, 2, 3 and 5. What is the probability that the number is divisible by 25, if repetition of digits is not allowed?
Explanation:
Total number of four-digit numbers that can be formed = 4!. If the number is divisible by 25, then the last two digits are 25. So the first two digits can be arranged in 2! ways. Hence, required probability = 2!4!=112.