The average amount of money collected by a group of pupils at a flag day event was $105. When another 15 pupils turned up to help, the total amount donated increased by $517 and the average amount of money collected became $82. 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 |
105 |
82 |
Total Value |
105 u + 517 |
82 u + 1230 |
Number of pupils at first = 1 u
Total amount collected by the pupils at first
= 1 u x 105
= 105 u
Total amount collected by the pupils in the end
= 82 x (1 u + 15)
= 82 u + 1230
105 u + 517 = 82 u + 1230
105 u - 82 u = 1230 - 517
23 u = 713
1 u = 713 ÷ 23 = 31
Number of pupils in the end
= 1 u + 15
= 31 + 15
= 46
Answer(s): 46