The average amount of money collected by a group of pupils at a flag day event was $115. When another 13 pupils turned up to help, the total amount donated increased by $604 and the average amount of money collected became $88. How many pupils were there in the group at first?
|
Number of pupils at first |
Number of pupils in the end |
Number |
1 u |
1 u + 13 |
Value |
115 |
88 |
Total Value |
115 u + 604 |
88 u + 1144 |
Number of pupils at first = 1 u
Total amount collected by the pupils at first
= 1 u x 115
= 115 u
Total amount collected by the pupils in the end
= 88 x (1 u + 13)
= 88 u + 1144
115 u + 604 = 88 u + 1144
115 u - 88 u = 1144 - 604
27 u = 540
1 u = 540 ÷ 27 = 20
Number of pupils at first
= 1 u
= 20
Answer(s): 20