Question

The price of commodity x increase by 40 paisa every year , while the price of commodity y increase by 15 paisa every year . If in 2001, the price of x was RS 4.20 and that of y was RS 6.30 in which year commodity x will cost 40 paisa more than the commodity y .

Answer 1

Suppose commodity X wil cost 40 paise more than Y after Z years. Then,
(4.20 + 0.40Z) - (6.30 + 0.15Z) = 0.40

(4.20-6.30)+(0.40-0.15)z=0.40

=> 0.25Z = 0.40 + 2.10

=> Z= 2.50/0.25 = 10
Therefore, X will cost 40 paise more than Y 10 years after 2001 . i.e in 2011