The average amount of money collected by a group of pupils at a flag day event was $110. When another 12 pupils turned up to help, the total amount donated increased by $682 and the average amount of money collected became $81. 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 + 12 |
Value |
110 |
81 |
Total Value |
110 u + 682 |
81 u + 972 |
Number of pupils at first = 1 u
Total amount collected by the pupils at first
= 1 u x 110
= 110 u
Total amount collected by the pupils in the end
= 81 x (1 u + 12)
= 81 u + 972
110 u + 682 = 81 u + 972
110 u - 81 u = 972 - 682
29 u = 290
1 u = 290 ÷ 29 = 10
Number of pupils in the end
= 1 u + 12
= 10 + 12
= 22
Answer(s): 22