Adam has 240 blue marbles.
He has 6 times as many blue marbles as red marbles.
After he buys an equal number of blue and red marbles,
the number of blue marbles is 3 times that of the red marbles.
- How many blue marbles are there in the end?
- How many red marbles are there in the end?
- How many marbles are there in the end?
- How many marbles does Adam buy?
|
Blue marbles |
Red marbles |
Difference |
Before |
6 x 2 = 12 u |
1 x 2 = 2 u |
5 x 2 = 10 u |
Change |
+ ? |
+ ? |
|
After |
3 x 5 = 15 u |
1 x 5 = 5 u |
2 x 5 = 10 u |
(a)
The difference in the number between the blue and red marbles at first and in the end remains unchanged.
LCM of 5 and 2 is 10.
12 u = 240
1 u = 240 ÷ 12 = 20
Number of blue marbles in the end
= 15 u
= 15 x 20
= 300
(b)
Number of red marbles in the end
= 5 u
= 5 x 20
= 100
(c)
Total number of marbles in the end
= 300 + 100
= 400
(d)
Total number of marbles that Adam buys
= (15 u - 12 u) x 2
= 3 u x 2
= 6 u
= 6 x 20
= 120
Answer(s): (a) 300; (b) 100; (c) 400; (d) 120