The average amount of money collected by a group of pupils at a flag day event was $108. When another 13 pupils turned up to help, the total amount donated increased by $606 and the average amount of money collected became $89. 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 + 13 |
Value |
108 |
89 |
Total Value |
108 u + 606 |
89 u + 1157 |
Number of pupils at first = 1 u
Total amount collected by the pupils at first
= 1 u x 108
= 108 u
Total amount collected by the pupils in the end
= 89 x (1 u + 13)
= 89 u + 1157
108 u + 606 = 89 u + 1157
108 u - 89 u = 1157 - 606
19 u = 551
1 u = 551 ÷ 19 = 29
Number of pupils in the end
= 1 u + 13
= 29 + 13
= 42
Answer(s): 42