The average amount of money collected by a group of students at a flag day event was $107. When another 15 students turned up to help, the total amount donated increased by $685 and the average amount of money collected became $87. How many students were there in the group in the end?
|
Number of students at first |
Number of students in the end |
Number |
1 u |
1 u + 15 |
Value |
107 |
87 |
Total Value |
107 u + 685 |
87 u + 1305 |
Number of students at first = 1 u
Total amount collected by the students at first
= 1 u x 107
= 107 u
Total amount collected by the students in the end
= 87 x (1 u + 15)
= 87 u + 1305
107 u + 685 = 87 u + 1305
107 u - 87 u = 1305 - 685
20 u = 620
1 u = 620 ÷ 20 = 31
Number of students in the end
= 1 u + 15
= 31 + 15
= 46
Answer(s): 46