The average amount of money collected by a group of pupils at a flag day event was $101. When another 9 pupils turned up to help, the total amount donated increased by $506 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 + 9 |
| Value |
101 |
88 |
| Total Value |
101 u + 506 |
88 u + 792 |
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
= 88 x (1 u + 9)
= 88 u + 792
101 u + 506 = 88 u + 792
101 u - 88 u = 792 - 506
13 u = 286
1 u = 286 ÷ 13 = 22
Number of pupils in the end
= 1 u + 9
= 22 + 9
= 31
Answer(s): 31
