The average amount of money collected by a group of pupils at a flag day event was $101. When another 9 pupils turned up to help, the total amount donated increased by $589 and the average amount of money collected became $85. 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 + 9 |
Value |
101 |
85 |
Total Value |
101 u + 589 |
85 u + 765 |
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
= 85 x (1 u + 9)
= 85 u + 765
101 u + 589 = 85 u + 765
101 u - 85 u = 765 - 589
16 u = 176
1 u = 176 ÷ 16 = 11
Number of pupils at first
= 1 u
= 11
Answer(s): 11