Business School Problem

[knight247]

At a business school conference with 100 attendees, are there any students of the same age(rounded to the nearest year) who attend the same school?

(1)The range of ages of the participants is 22 to 30, inclusive
(2)Participants represent 10 business schools

[cans]

100 attendees.
A) Maybe attendees are all from different schools. or maybe same Insufficient
B) on average, 10 attendees per school. there age can be 21,22...30 or 21,21,...21
Insufficient

A&B) range=22 to 30: 22,23...30 (total 9 ages..)
also 10 business schools. therefore atleast one school will have more than 9 attendees. otherwise total will be only 90 max. Let that school be A.
Now A has 10 students and we have only 9 different ages. Thus atleast 2 students will have same age. Sufficient
IMO C

[mehrasa]

nothing to explain more.. gr8 explanation Mrs cans.. good job