Adam has 255 red marbles.
He has 5 times as many red marbles as blue marbles.
After he buys an equal number of red and blue marbles,
the number of red marbles is 4 times that of the blue marbles.
- How many red marbles are there in the end?
- How many blue marbles are there in the end?
- How many marbles are there in the end?
- How many marbles does Adam buy?
|
Red marbles |
Blue marbles |
Difference |
Before |
5 x 3 = 15 u |
1 x 3 = 3 u |
4 x 3 = 12 u |
Change |
+ ? |
+ ? |
|
After |
4 x 4 = 16 u |
1 x 4 = 4 u |
3 x 4 = 12 u |
(a)
The difference in the number between the red and blue marbles at first and in the end remains unchanged.
LCM of 4 and 3 is 12.
15 u = 255
1 u = 255 ÷ 15 = 17
Number of red marbles in the end
= 16 u
= 16 x 17
= 272
(b)
Number of blue marbles in the end
= 4 u
= 4 x 17
= 68
(c)
Total number of marbles in the end
= 272 + 68
= 340
(d)
Total number of marbles that Adam buys
= (16 u - 15 u) x 2
= 1 u x 2
= 2 u
= 2 x 17
= 34
Answer(s): (a) 272; (b) 68; (c) 340; (d) 34