The average amount of money collected by a group of pupils at a flag day event was $108. When another 15 pupils turned up to help, the total amount donated increased by $600 and the average amount of money collected became $88. 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 |
108 |
88 |
Total Value |
108 u + 600 |
88 u + 1320 |
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
= 88 x (1 u + 15)
= 88 u + 1320
108 u + 600 = 88 u + 1320
108 u - 88 u = 1320 - 600
20 u = 720
1 u = 720 ÷ 20 = 36
Number of pupils in the end
= 1 u + 15
= 36 + 15
= 51
Answer(s): 51