The average amount of money collected by a group of pupils at a flag day event was $100. When another 13 pupils turned up to help, the total amount donated increased by $598 and the average amount of money collected became $87. 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 |
100 |
87 |
Total Value |
100 u + 598 |
87 u + 1131 |
Number of pupils at first = 1 u
Total amount collected by the pupils at first
= 1 u x 100
= 100 u
Total amount collected by the pupils in the end
= 87 x (1 u + 13)
= 87 u + 1131
100 u + 598 = 87 u + 1131
100 u - 87 u = 1131 - 598
13 u = 533
1 u = 533 ÷ 13 = 41
Number of pupils in the end
= 1 u + 13
= 41 + 13
= 54
Answer(s): 54