Question

A machine takes $2$ litres of petrol to start and then $3$ litres per hour while running. Write a linear equation for the amount of petrol used by taking amount of petrol (in litres) as $y$ and no. of running hours as $x$.

• A. $y=3x$
• B. $y=2x+3$
• C. $y=3x+2$
• D. $y=2x$

Answer 1

Answer: (C)

$y=3x+2$

Let the total running hours be x. It is given that the machine consumes 3 litres of petrol per hour while running.
Hence for x hours of running it will consume $3x$ litres of petrol. It is also given that it consumes an additional 2 litres of petrol to start. Hence for x hours of running it will consume in total $3x+2$ litres of petrol.
Thus for x hours of running if y is the amount of petrol required then
$y=3x+2$.