Question

3/10:Vicky has 11 keys, and there are 11 different lockers, and the 11 keys to open the 11 lockers are mixed together. How many times at most will Vicky have to try to match these 11 lockers with the right keys?​

Answer 1

Explanation:

More than you might think.

She takes 1 key in her hand. It might take her 11 tries to find the right locker

Now she knows there are 10 other lockers that will be opened by the key in her hand.

So far that's 11 * 10 = 110

Now she has 9 lockers for the 3rd key. She might need to check all 9 of them before she finds the right one

9 * 110 = 990 tries for the first 3 keys.

11 * 10 * 9 * 8 * 7 * 6 * 5 * 4 * 3 * 2 * 1 = 39 916 800

She will be busy until well after the birth of her first child -- and then some.