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?

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Solution

## 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 = $60×12=720\mathrm{km}$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}$So, the difference in the speed,=$\left(72-60\right)\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 $10\mathrm{hours}.$

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