The average amount of money collected by a group of pupils at a flag day event was $104. When another 11 pupils turned up to help, the total amount donated increased by $524 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 + 11 |
Value |
104 |
84 |
Total Value |
104 u + 524 |
84 u + 924 |
Number of pupils at first = 1 u
Total amount collected by the pupils at first
= 1 u x 104
= 104 u
Total amount collected by the pupils in the end
= 84 x (1 u + 11)
= 84 u + 924
104 u + 524 = 84 u + 924
104 u - 84 u = 924 - 524
20 u = 400
1 u = 400 ÷ 20 = 20
Number of pupils at first
= 1 u
= 20
Answer(s): 20