The average amount of money collected by a group of students at a flag day event was $103. When another 15 students turned up to help, the total amount donated increased by $791 and the average amount of money collected became $90. How many students were there in the group at first?
|
Number of students at first |
Number of students in the end |
Number |
1 u |
1 u + 15 |
Value |
103 |
90 |
Total Value |
103 u + 791 |
90 u + 1350 |
Number of students at first = 1 u
Total amount collected by the students at first
= 1 u x 103
= 103 u
Total amount collected by the students in the end
= 90 x (1 u + 15)
= 90 u + 1350
103 u + 791 = 90 u + 1350
103 u - 90 u = 1350 - 791
13 u = 559
1 u = 559 ÷ 13 = 43
Number of students at first
= 1 u
= 43
Answer(s): 43