Class U, V and W were given some mochi balls to sell for their fund-raising project. The average number of mochi balls the 3 classes had at first was 246. After Class V sold twice as many mochi balls as Class U and Class W sold
78 as many mochi balls as Class V, the average number of mochi balls the 3 classes had left was 56. How many mochi balls did Class U and Class W sell altogether?
Class U |
Class V |
Class W |
1x4 |
2x4 |
|
|
8x1 |
7x1 |
4 u |
8 u |
7 u |
Class U : Class V : Class W
4 : 8 : 7
Total number of mochi balls that the 3 classes had at first
= 3 x 246
= 738
Number of mochi balls that the 3 classes left
= 3 x 56
= 168
Number of mochi balls that were sold by 3 classes
= 738 - 168
= 570
4 u + 8 u + 7 u = 570
19 u = 570
1 u = 570 ÷ 19 = 30
Total number of mochi balls sold by Class U and Class W
= 4 u + 7 u
= 11 u
= 11 x 30
= 330
Answer(s): 330