The average amount of money collected by a group of pupils at a flag day event was $101. When another 15 pupils turned up to help, the total amount donated increased by $655 and the average amount of money collected became $81. How many pupils were there in the group in the end?
|
Number of pupils at first |
Number of pupils in the end |
Number |
1 u |
1 u + 15 |
Value |
101 |
81 |
Total Value |
101 u + 655 |
81 u + 1215 |
Number of pupils at first = 1 u
Total amount collected by the pupils at first
= 1 u x 101
= 101 u
Total amount collected by the pupils in the end
= 81 x (1 u + 15)
= 81 u + 1215
101 u + 655 = 81 u + 1215
101 u - 81 u = 1215 - 655
20 u = 560
1 u = 560 ÷ 20 = 28
Number of pupils in the end
= 1 u + 15
= 28 + 15
= 43
Answer(s): 43