Question

1. A school has 10 classes with the same number of students in each class. One day, the weather was bad and many students were absent. 5 classes were half full, 3 classes were 3/4 full and 2 classes were 1/8 empty. A total of 70 students were absent. How many students are in this school when no students are absent?

2. A telephone company charges initially $0.50 and then $0.11 for every minute. Write an expression that gives the cost of a call that lasts N minutes.

Answer 1

N - number of students in one class
70 - number of absent students
absent in each of the classes:
5 x 1/2N - 5 classes were half full,
3 x 1/4N - 3 classes were 3/4 full
2 x 1/8N - 2 classes were 1/8 empty

(5 x 1/2N) + (3 x 1/4N) + (2 x 1/8N) = 70
N = ?

How many students are in this school when no students are absent?
10 x N