One boy forgot the last digit of a 7digit telephone no. If he randomly dial the final 3digits after correctly dialing the 1st 4, then what is the chance of dialing the correct no.?
Select
A) 1/989 B) 2/890 C) 1/1000 D) 3/890 E) 4/981
it is given that last 3 digits are randomly dialed   Then, each of the digit can be selected out of 10 digits in 10 ways. Hence, required probability   = 1/(10)3 = 1/1000   1/1000
<result>C</result>
One boy forgot the last digit of a 7digit telephone no. If he randomly dial the final 3digits after correctly dialing the 1st 4, then what is the chance of dialing the correct no.?