Question

1 forgot the last digit of a 7-digit telephone number. If 1 randomly dial the final 3 digits after correctly dialing the first four, then what is the chance of dialing the correct number?

Options

• `1/999`

• `1/1001`

• `1/1000`

• `4/1000`

Answer 1

`1/1000`

Explanation:
It is given that the last three digits are randomly dialed.
Then each of the digits can be selected out of 10 digits in 10 ways.

Hence, required probability = `(1/10)^3=1/1000`