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

A.

1/1001

B.

1/1000

C.

1/999

D.

1/990

• total prob. = 1*1*1*1*10*10*10 = 1000
  
  Prob of dialing correct no. = 1/1000
  
• 9 years agoHelpfull: Yes(1) No(1)