In a box, there are balls of color red, black and white in the ratio of 14 ∶ 21 ∶ 10, now 12 red, 18 black and 7 white balls are removed an… — Answer & Discussion

In a box, there are balls of color red, black and white in the ratio of 14 ∶ 21 ∶ 10, now 12 red, 18 black and 7 white balls are removed and now the ratio becomes 4 ∶ 6 ∶ 3. Now, how many balls are left in the box after removal?

A171
B166
C151
D143

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Discussion 1

CCommunity15 Jul 2019

Red ? Black ? White = 14 ? 21 ? 10

Thus, let red, black, white balls be 14x, 21x, 10x.

Now, 12 red, 18 black and 7 white balls are removed.

Thus, 14x - 12 ? 21x - 18 ? 10x - 7 = 4 ? 6 ? 3

∴ 21x - 18 ? 10x - 7 = 6 ? 3 = 2 ? 1

∴ (21x - 18) = 2(10x - 7)

∴ 21x - 18 = 20x - 14

∴ x = 4

Total number of balls = 14(4) - 12 + 21(4) - 18 + 10(4) - 7 = 143