The average amount of money collected by a group of students at a flag day event was $105. When another 13 students turned up to help, the total amount donated increased by $689 and the average amount of money collected became $79. 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 |
105 |
79 |
Total Value |
105 u + 689 |
79 u + 1027 |
Number of students at first = 1 u
Total amount collected by the students at first
= 1 u x 105
= 105 u
Total amount collected by the students in the end
= 79 x (1 u + 13)
= 79 u + 1027
105 u + 689 = 79 u + 1027
105 u - 79 u = 1027 - 689
26 u = 338
1 u = 338 ÷ 26 = 13
Number of students at first
= 1 u
= 13
Answer(s): 13