The average amount of money collected by a group of students at a flag day event was $110. When another 11 students turned up to help, the total amount donated increased by $643 and the average amount of money collected became $89. 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 |
110 |
89 |
| Total Value |
110 u + 643 |
89 u + 979 |
Number of students at first = 1 u
Total amount collected by the students at first
= 1 u x 110
= 110 u
Total amount collected by the students in the end
= 89 x (1 u + 11)
= 89 u + 979
110 u + 643 = 89 u + 979
110 u - 89 u = 979 - 643
21 u = 336
1 u = 336 ÷ 21 = 16
Number of students in the end
= 1 u + 11
= 16 + 11
= 27
Answer(s): 27
