The average amount of money collected by a group of students at a flag day event was $102. When another 13 students turned up to help, the total amount donated increased by $717 and the average amount of money collected became $81. 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 + 13 |
Value |
102 |
81 |
Total Value |
102 u + 717 |
81 u + 1053 |
Number of students at first = 1 u
Total amount collected by the students at first
= 1 u x 102
= 102 u
Total amount collected by the students in the end
= 81 x (1 u + 13)
= 81 u + 1053
102 u + 717 = 81 u + 1053
102 u - 81 u = 1053 - 717
21 u = 336
1 u = 336 ÷ 21 = 16
Number of students at first
= 1 u
= 16
Answer(s): 16