Question

If the price of petrol be raised by
12.5%, find by what percentage
should a consumer decrease the
consumption of petrol so that
there is no change in his
monthly expenditure on petrol ?
(bi
4504​

Answer 1

$\bf{\underline{\underline{\bigstar\bigstar\: Solution : }}}$

$\:\:$

$\footnotesize{ Price \: of \: petrol \: raise = 12.5 \% }$

$\footnotesize{\implies Rate ( R ) = 12.5 \% }$

$\:\:$

$\boxed{\rule{200}3}$

$\:\:$

$\footnotesize{ Consumption \: of \: petrol \: decrease = \dfrac{ R}{100 + R} \times 100 \% }$

$\footnotesize{\implies Consumption \: of \: petrol \: decrease = \dfrac{12.5}{100 + 12.5} \times 100 \% }$

$\footnotesize{\implies Consumption \: of \: petrol \: decrease = \dfrac{12.5}{112.5} \times 100 \% }$

$\footnotesize{\implies Consumption \: of \: petrol \: decrease = \dfrac{100}{9} \% }$

$\footnotesize{\implies Consumption \: of \: petrol \: decrease = 11\dfrac{1}{9} \% \: or \: 11.1 \% }$

$\:\:$

$\footnotesize{\bold{\underline{\bigstar Consumption \: of \: petrol \: decrease \: is \: 11\dfrac{1}{9} \% \: or \: 11.1 \% }}}$