Question

There are 1313 people in an office with 66 different phone lines. if all the lines begin to ring at once, how many groups of 66 people can answer these lines?

Answer 1

Number of people in the office=13
Number of office lines=66
Given that all the 6 phones started ringing at once, the number of groups of 6 people that that can answer the lines will be:
13C6
=(13!)/(6!7!)
=1,716