The number of red, blue, and green marbles in a bag is in the ratio 3 : 4 : 6.…
2025
The number of red, blue, and green marbles in a bag is in the ratio 3 : 4 : 6. If 20 red marbles, 15 blue
marbles, and an unknown number of green marbles are added to the bag, the ratio of red, blue, and green marbles
becomes 4 : 5 : 7. Determine the number of green marbles added.
- A.
3
- B.
5
- C.
7
- D.
9
Attempted by 13 students.
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Correct answer: B
Let the initial numbers of red, blue and green marbles be 3x, 4x and 6x. From (3x + 20):(4x + 15) = 4:5, x = 40. The new red count is 140, so one part is 35 and the final green count should be 7 x 35 = 245. Initial green count is 240, so 5 green marbles were added.