Let the work done by (x-1) men in (x+1) days be y. Let the work done by (x+2) men in (x-1) days be z. If y:z=9:10 then what is the value of x?

Explanation

The work done is proportional to the product of men and days. Thus, y = (x-1)(x+1) and z = (x+2)(x-1). The ratio \frac{y}{z} = \frac{x+1}{x+2} = \frac{9}{10}. Cross-multiplying gives 10x + 10 = 9x + 18, which simplifies to x = 8. Note: There was a typo in the official paper in the English version but it was correct in the Hindi version.

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