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Simplification Test 5

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Question : 28 of 40

Marks: +1, -0

A certain number of tennis balls were purchased for Rs. 450. Five more balls could have been purchased in the same amount if each ball was cheaper by Rs. 15. Find the number of balls which was purchased.

25
20
15
10

Solution:

Let original cost of each tennis ball = Rs. x

Now,

\frac{450}{x-15} - \frac{450}{x} = 5

\Rightarrow \frac{90(x-x+15)}{x(x-15)} = 1

\Rightarrow x^2 - 15x - 1350 = 0

\Rightarrow x^2 - 45x + 30x - 1350 = 0

\Rightarrow x(x-45) + 30(x-45) = 0

\Rightarrow (x-45)(x+30) = 0

Either, x = 45 or, x = – 30 (Impossible)

Hence, number of balls purchased

= \frac{450}{45} = 10

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