The average amount of money collected by a group of students at a flag day event was $108. When another 13 students turned up to help, the total amount donated increased by $990 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 + 13 |
Value |
108 |
90 |
Total Value |
108 u + 990 |
90 u + 1170 |
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 + 13)
= 90 u + 1170
108 u + 990 = 90 u + 1170
108 u - 90 u = 1170 - 990
18 u = 180
1 u = 180 ÷ 18 = 10
Number of students in the end
= 1 u + 13
= 10 + 13
= 23
Answer(s): 23