Question

There are 20 locks and 20 matching keys. Maximum number of trials required to match all the locks is

Answer 1

Answer:

190 trials

Step-by-step explanation:

1st lock will need = N-1 tries [i.e. last no. of key not need to compare ]

2nd will need= N-2 tries

.

.

.

(N-1)th locks need =

So, total tries = N-1+N-2 +N-3 + ..... 1

=

1st lock will need = N-1 tries [i.e. last no. of key not need to compare ]

2nd will need= N-2 tries

.

.

.

(N-1)th locks need =

So, total tries = N-1+N-2 +N-3 + ..... 1

= ∑N−1n=1

= (N−1)N/2

so (20 *19)/2= 190