The price of commodity X increases by 40 paise every year, while the price of commodity Y increases by 15 paise every year. If in 2004, the price of commodity X was ₹ 4.20 and that of Y was ₹ 6.30, in which year commodity X will cost 40 paise more than the commodity Y?
(a)2013
(b)2014
(c)2015
(d)2016
Answer
Answer (as printed): B
Explanation
Suppose commodity $X$ will cost 40 paise more than $Y$ after $z$ years. Then, $$\begin{aligned} & (4.20+0.40 z)-(6.30+0.15 z)=0.40 \\ & \Leftrightarrow \quad 0.25 z=0.40+2.10 \quad \Leftrightarrow \quad z=\frac{2.50}{0.25}=\frac{250}{25}=10 . \end{aligned}$$ ∴ X will cost 40 paise more than Y 10 years after 2004 i.e., in 2014.
Explanation as extracted from the printed page; notation may be imperfect.