The average amount of money collected by a group of pupils at a flag day event was $111. When another 13 pupils turned up to help, the total amount donated increased by $555 and the average amount of money collected became $74. 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 + 13 |
Value |
111 |
74 |
Total Value |
111 u + 555 |
74 u + 962 |
Number of pupils at first = 1 u
Total amount collected by the pupils at first
= 1 u x 111
= 111 u
Total amount collected by the pupils in the end
= 74 x (1 u + 13)
= 74 u + 962
111 u + 555 = 74 u + 962
111 u - 74 u = 962 - 555
37 u = 407
1 u = 407 ÷ 37 = 11
Number of pupils in the end
= 1 u + 13
= 11 + 13
= 24
Answer(s): 24