Adam has 160 red marbles.
He has 4 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 3 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 |
4 x 2 = 8 u |
1 x 2 = 2 u |
3 x 2 = 6 u |
Change |
+ ? |
+ ? |
|
After |
3 x 3 = 9 u |
1 x 3 = 3 u |
2 x 3 = 6 u |
(a)
The difference in the number between the red and blue marbles at first and in the end remains unchanged.
LCM of 3 and 2 is 6.
8 u = 160
1 u = 160 ÷ 8 = 20
Number of red marbles in the end
= 9 u
= 9 x 20
= 180
(b)
Number of blue marbles in the end
= 3 u
= 3 x 20
= 60
(c)
Total number of marbles in the end
= 180 + 60
= 240
(d)
Total number of marbles that Adam buys
= (9 u - 8 u) x 2
= 1 u x 2
= 2 u
= 2 x 20
= 40
Answer(s): (a) 180; (b) 60; (c) 240; (d) 40