The average amount of money collected by a group of students at a flag day event was $109. When another 13 students turned up to help, the total amount donated increased by $505 and the average amount of money collected became $71. 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 |
109 |
71 |
Total Value |
109 u + 505 |
71 u + 923 |
Number of students at first = 1 u
Total amount collected by the students at first
= 1 u x 109
= 109 u
Total amount collected by the students in the end
= 71 x (1 u + 13)
= 71 u + 923
109 u + 505 = 71 u + 923
109 u - 71 u = 923 - 505
38 u = 418
1 u = 418 ÷ 38 = 11
Number of students in the end
= 1 u + 13
= 11 + 13
= 24
Answer(s): 24