The average amount of money collected by a group of students at a flag day event was $115. When another 13 students turned up to help, the total amount donated increased by $659 and the average amount of money collected became $77. 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 |
115 |
77 |
Total Value |
115 u + 659 |
77 u + 1001 |
Number of students at first = 1 u
Total amount collected by the students at first
= 1 u x 115
= 115 u
Total amount collected by the students in the end
= 77 x (1 u + 13)
= 77 u + 1001
115 u + 659 = 77 u + 1001
115 u - 77 u = 1001 - 659
38 u = 342
1 u = 342 ÷ 38 = 9
Number of students at first
= 1 u
= 9
Answer(s): 9