Question

A typical PIN is a sequence of any four symbols chosen from 26 letters in alphabet and ten digits. If all the pirate equally likely, find probability that a random choosen PIN contain repeated symbol.

Answer 1

this question is of Maths 9 Geography please try and edit it forgetting the correct answer.....

Answer 2

Answer :- 0.158

Since the PIN is for 4 symbols say A B C D

For each of A / B / C / D there are following possibilities 26 letters + 10 digits = 36

Total number of PIN possible including all combinations = 36 x 36 x 36 x 36 = 1,679,616.

Now consider a scenario where there are no repeated number. So total number of PIN combinations will be = 36 x 35 x 34 x 33 = 1,413,720

So the combination where there will be repeated symbol will be = 1,679,616 - 1,413,720 = 2,65,896

Probability that random chosen PIN contains repeated symbol = 2,65,896 / 1,679,616 = 0.158