Question

A letter lock consists of three rings each marked with 10 different letters. In how many ways it is possible to make an unsuccessful attempt to open the lock?

Answer 1

Total number of ways to make an attempt to open the lock is = 10 × 10 × 10 = 1000

Number of successful attempts to open the lock = 1

Number of unsuccessful attempts to open the lock = 1000 – 1 = 999

Thus, required number of possible ways to make an unsuccessful attempt to open the lock is 999.