Question

A 5-digit number is formed by the digits 2,4,5,6,8 (each digit used exactly once) . What is the probability that the number formed is divisible by 4 ?

Answer 1

P = Number of desired outcomes / number of possible outcomes

Number of desired outcomes:

To be divisible by 4, the number has to end with the last two digits forming a number divisible by 4. Given the numbers in the question this leaves us with:

12

24

32

52

For each of them I now have to put the remaining numbers in front: 3x2x1 --> 6 combinations for each number set = 6x4 (we have 4 sets from above) = 24

Number of possible outcomes:

The total number of possibilities to form a 5 digit number from the question= 5x4x3x2x1=120

P = 24/120 = 1/5 --> A