The average amount of money collected by a group of pupils at a flag day event was $101. When another 13 pupils turned up to help, the total amount donated increased by $809 and the average amount of money collected became $80. 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 |
101 |
80 |
| Total Value |
101 u + 809 |
80 u + 1040 |
Number of pupils at first = 1 u
Total amount collected by the pupils at first
= 1 u x 101
= 101 u
Total amount collected by the pupils in the end
= 80 x (1 u + 13)
= 80 u + 1040
101 u + 809 = 80 u + 1040
101 u - 80 u = 1040 - 809
21 u = 231
1 u = 231 ÷ 21 = 11
Number of pupils in the end
= 1 u + 13
= 11 + 13
= 24
Answer(s): 24
