The average amount of money collected by a group of pupils at a flag day event was $117. When another 15 pupils turned up to help, the total amount donated increased by $887 and the average amount of money collected became $89. 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 + 15 |
Value |
117 |
89 |
Total Value |
117 u + 887 |
89 u + 1335 |
Number of pupils at first = 1 u
Total amount collected by the pupils at first
= 1 u x 117
= 117 u
Total amount collected by the pupils in the end
= 89 x (1 u + 15)
= 89 u + 1335
117 u + 887 = 89 u + 1335
117 u - 89 u = 1335 - 887
28 u = 448
1 u = 448 ÷ 28 = 16
Number of pupils in the end
= 1 u + 15
= 16 + 15
= 31
Answer(s): 31