The average amount of money collected by a group of students at a flag day event was $107. When another 15 students turned up to help, the total amount donated increased by $957 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 + 15 |
Value |
107 |
89 |
Total Value |
107 u + 957 |
89 u + 1335 |
Number of students at first = 1 u
Total amount collected by the students at first
= 1 u x 107
= 107 u
Total amount collected by the students in the end
= 89 x (1 u + 15)
= 89 u + 1335
107 u + 957 = 89 u + 1335
107 u - 89 u = 1335 - 957
18 u = 378
1 u = 378 ÷ 18 = 21
Number of students in the end
= 1 u + 15
= 21 + 15
= 36
Answer(s): 36