The average amount of money collected by a group of students at a flag day event was $108. When another 11 students turned up to help, the total amount donated increased by $648 and the average amount of money collected became $90. 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 + 11 |
Value |
108 |
90 |
Total Value |
108 u + 648 |
90 u + 990 |
Number of students at first = 1 u
Total amount collected by the students at first
= 1 u x 108
= 108 u
Total amount collected by the students in the end
= 90 x (1 u + 11)
= 90 u + 990
108 u + 648 = 90 u + 990
108 u - 90 u = 990 - 648
18 u = 342
1 u = 342 ÷ 18 = 19
Number of students in the end
= 1 u + 11
= 19 + 11
= 30
Answer(s): 30