The average amount of money collected by a group of pupils at a flag day event was $106. When another 14 pupils turned up to help, the total amount donated increased by $780 and the average amount of money collected became $84. 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 + 14 |
Value |
106 |
84 |
Total Value |
106 u + 780 |
84 u + 1176 |
Number of pupils at first = 1 u
Total amount collected by the pupils at first
= 1 u x 106
= 106 u
Total amount collected by the pupils in the end
= 84 x (1 u + 14)
= 84 u + 1176
106 u + 780 = 84 u + 1176
106 u - 84 u = 1176 - 780
22 u = 396
1 u = 396 ÷ 22 = 18
Number of pupils at first
= 1 u
= 18
Answer(s): 18