The average amount of money collected by a group of students at a flag day event was $104. When another 15 students turned up to help, the total amount donated increased by $720 and the average amount of money collected became $89. How many students were there in the group at first?
|
Number of students at first |
Number of students in the end |
Number |
1 u |
1 u + 15 |
Value |
104 |
89 |
Total Value |
104 u + 720 |
89 u + 1335 |
Number of students at first = 1 u
Total amount collected by the students at first
= 1 u x 104
= 104 u
Total amount collected by the students in the end
= 89 x (1 u + 15)
= 89 u + 1335
104 u + 720 = 89 u + 1335
104 u - 89 u = 1335 - 720
15 u = 615
1 u = 615 ÷ 15 = 41
Number of students at first
= 1 u
= 41
Answer(s): 41