Question

The cost of 140 tennis balls is Rs 4900. Find the cost of 2 dozen such balls.

Answer 1

Let Rs x be the cost of 24 tennis balls.

No. of balls	140	24
Cost of balls	4900	$x$

More tennis balls will cost more.
$$\begin{gathered} \mathrm{Now},\frac{140}{4900}=\frac{24}{x} \\ \Rightarrow x=\frac{24\times 4900}{140} \\ \Rightarrow x=840 \end{gathered}$$

∴ The cost of 2 dozen tennis balls is Rs 840.