CA Foundation · Quantitative Aptitude · Equations
A trader buys x articles for ₹1,200. If he had bought 10 more articles for the same amount, the cost per article would have been ₹4 less. How many articles did he buy?
He bought 50 articles. The condition 1200/x − 1200/(x + 10) = 4 gives x² + 10x − 3000 = 0, so x = 50. The cost per article is then ₹24, and with 60 articles it would be ₹20, which is ₹4 less.
- A25
- B20
- C40
- D30Correct
Explanation
The equation is 1200/x − 1200/(x + 10) = 4. This gives 12000 = 4x(x + 10), so x² + 10x − 3000 = 0. Wait: 12000/4 = 3000, which factors as (x + 60)(x − 50) = 0, so x = 50. Check: 1200/50 = 24 and 1200/60 = 20, a difference of 4. So he bought 50 articles.
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