If any four numbers are slected and they are multiplied, then the probability that the last digit will be `1,3,5 or 7` is

Options

A. `4//625`
B. `18//625`
C. `16//625`
D. None of these

Answer

C

Explanation

The total number of digits in any number at eh unit's place is 10. Therefore,
`n(S)=10`
If the last digit in product is `1,3,5 or 7,` then it is necessary that the last digit in each number must be `1,3,5or 7.` Therefore, `(n)A=4`
`thereforeP(A)=4/10=2/5`
Hence, the required probability is `(2//5)^(4)=16//625.`