Question

Rohit bought 12 registers for Rs 156, find the cost of 7 such registers.

 

Answer 1

Let the cost of 7 registers be​ Rs x.
 

Register	12	7
Cost(in Rs.)	156	x

\[\text{ If he buys less number of registers, the cost will also be less }  . \]
\[\text{ Therefore, it is a direct variation .}  \]
\[\text{ We get: }  \]
\[12: 7 = 156: x\]
\[ \Rightarrow \frac{12}{7} = \frac{156}{x}\]
\[ \text{ Applying cross muliplication, we get: }  \]
\[x = \frac{156 \times 7}{12}\]
\[ = 91\]
\[\text{ Thus, the cost of 7 such registers will be Rs 91 } .\]