The average amount of money collected by a group of pupils at a flag day event was $110. When another 10 pupils turned up to help, the total amount donated increased by $572 and the average amount of money collected became $86. 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 + 10 |
| Value |
110 |
86 |
| Total Value |
110 u + 572 |
86 u + 860 |
Number of pupils at first = 1 u
Total amount collected by the pupils at first
= 1 u x 110
= 110 u
Total amount collected by the pupils in the end
= 86 x (1 u + 10)
= 86 u + 860
110 u + 572 = 86 u + 860
110 u - 86 u = 860 - 572
24 u = 288
1 u = 288 ÷ 24 = 12
Number of pupils in the end
= 1 u + 10
= 12 + 10
= 22
Answer(s): 22
