Question

If 16 bicycles cost Rs 17,600, how much will 9 such bicycles cost?

Answer 1

Cost of 16 bicycles = Rs 17,600.
Let the cost of 9 bicycles be Rs x.
The given information can be represented in the following table:

Cost of bicycles (in Rs) : x	17600	x
Number of bicycles : y	16	9

Here, cost of bicycles and number of bicycles are in direct proportion because cost of bicycles will decrease with a decrease in the number of bicycles. In direct variation, the ratio of the cost of bicycles to the number of bicycles must be constant,i.e
$$\begin{gathered} \frac{x_1}{y_1}=\frac{x_2}{y_2} \\ \therefore \frac{17600}{16}=\frac{x}{9} \\ x=\frac{17600}{16}\times 9=\mathrm{Rs}9900 \end{gathered}$$
Thus, cost of 9 bicycles is Rs 9900.