Question

Two mobiles cost 16,000 rupees. How much money will be required to buy 13 such mobiles ?

Answer 1

Let us suppose the cost of 13 mobiles is x rupees.
The number of mobiles and their cost vary in direct proportion.
$$\begin{gathered} \therefore \frac{2}{16000}=\frac{13}{x} \\ \Rightarrow x=\frac{13\times 16000}{2} \end{gathered}$$
= 104000 rupees
Hence, the cost of 13 mobiles is 104000 rupees.