The average amount of money collected by a group of pupils at a flag day event was $101. When another 15 pupils turned up to help, the total amount donated increased by $955 and the average amount of money collected became $85. How many pupils were there in the group in the end?
|
Number of pupils at first |
Number of pupils in the end |
Number |
1 u |
1 u + 15 |
Value |
101 |
85 |
Total Value |
101 u + 955 |
85 u + 1275 |
Number of pupils at first = 1 u
Total amount collected by the pupils at first
= 1 u x 101
= 101 u
Total amount collected by the pupils in the end
= 85 x (1 u + 15)
= 85 u + 1275
101 u + 955 = 85 u + 1275
101 u - 85 u = 1275 - 955
16 u = 320
1 u = 320 ÷ 16 = 20
Number of pupils in the end
= 1 u + 15
= 20 + 15
= 35
Answer(s): 35