Algebra with applications
posted by lyn .
A poll was taken of 100 students at a commuter campus to find out how they got to campus. The results were as follows:
23 said they drove alone.
30 rode in a carpool.
31 rode public transportation.
4 used both carpools and public transportation.
3 used both a carpool and sometimes their own cars.
3 used buses as well as their own cars.
1 used all three methods.
How many used none of the above-mentioned means of transportation?
drove alone --- A
carpool ------- B
public trans ----C
number(A or B or C) = number A + number B + number C - Number (AandB) - number (Aand C) - number (Band C) + number (AndBandC)
= 23 +30 +31 - 4 - 3 - 3 + 1
so 100 - 75 or 25 used none of the above