Class A, B and C were given some mini cupcakes to sell for their fund-raising project. The average number of mini cupcakes the 3 classes had at first was 242. After Class B sold twice as many mini cupcakes as Class A and Class C sold
67 as many mini cupcakes as Class B, the average number of mini cupcakes the 3 classes had left was 55. How many mini cupcakes did Class A and Class C sell altogether?
Class A |
Class B |
Class C |
1x7 |
2x7 |
|
|
7x2 |
6x2 |
7 u |
14 u |
12 u |
Class A : Class B : Class C
7 : 14 : 12
Total number of mini cupcakes that the 3 classes had at first
= 3 x 242
= 726
Number of mini cupcakes that the 3 classes left
= 3 x 55
= 165
Number of mini cupcakes that were sold by 3 classes
= 726 - 165
= 561
7 u + 14 u + 12 u = 561
33 u = 561
1 u = 561 ÷ 33 = 17
Total number of mini cupcakes sold by Class A and Class C
= 7 u + 12 u
= 19 u
= 19 x 17
= 323
Answer(s): 323