Word Problem No.3 (Compound Proportion) --- Length, Width, and Price (Compound Proportion among three quantities)

If the price of a carpet 8 metres long and 3 metres wide is Rs. 6288, what will be the price of 12 metres long and 6 metre wide carpet? 

Solution: 

As the length of carpet increase, the price will also increase. It is a direct proportion. 

As the width increase, the price will also increase. It is also a direct proportion. 

Let the price be ｘ

Here the equation will be 

`\frac{ｘ}{6,288}`  = `\frac{6}{3}` ｘ `\frac{12}{8}` 

Or

ｘ = `\frac{6}{3}` ｘ `\frac{12}{8}`  ｘ 6,288 Rs.

by simplifying we get

ｘ =  18,864 Rs.

Thus, the price of carpet will increase to  18,864 Rs.