Question

A car can reach a certain place in 12 hours at a speed of 60 km per hour. By how much should the speed be increased so that it completes the journey in 10 hours?

Answer 1

Step 1:

Given,

Speed of the car = $60\mathrm{km}/\mathrm{h}$

Time is taken by the car = $12\mathrm{hours}$

Distance to be travelled = $60\times 12=720\mathrm{km}$

Step 2:

Therefore, the speed to be increased in $10\mathrm{hours}$=

$\mathrm{speed}=\frac{\mathrm{distance}}{\mathrm{time}}$

$\mathrm{speed}=\frac{720\mathrm{km}}{10\mathrm{h}}$

$\mathrm{speed}=72\mathrm{km}/\mathrm{h}$

So, the difference in the speed,

=$(72-60)\mathrm{km}/\mathrm{h}=12\mathrm{km}/\mathrm{h}$

Therefore, the speed should be increased by $12\mathrm{km}/\mathrm{h}$ so that it completes the journey in $10\mathrm{hours}.$