Question

A car is travelling on a national Highway it travels 30 km at a uniform speed of 40 km per hour and the next 30 km at a uniform speed of 20 km per hour find its average speed

Answer 1

Given : -

•A car travels 30km at a uniform speed.

• Speed of the car is 40km/hr.

•Next 30km at a uniform speed of 20km/hr.

To Find : -

•Find the average speed of the car.

Solution : -

Given,

• Distance = 30km
• Speed = 40km/hr

As we know,

$\: \: \large \sf \: time = \frac{distance}{speed}$

Now substitute the values

$\: \sf \implies \: time = \frac{30}{40} \\ \\ \: \: \sf \implies \: time = \frac{3}{4} hour$

Given,

• Distance = 30km
• Speed = 20km/hr

As we know

$\: \: \sf \large \: time = \frac{distance}{speed}$

Now substitute the values

$\: \: \sf \implies time = \frac{30}{20} \\ \\ \: \: \sf \implies \: time = \frac{3}{2} hour$

Now,

$\: \sf \implies \: total \: time = ( \frac{3}{4} + \frac{3}{2} ) \\ \\ \: \: \sf \implies \: total \: time = \frac{9}{4} hour$

Now,

$\sf \large \implies \: average \: speed = \frac{total \: distance}{total \: time}$

Now substitute the values

$\: \sf \implies \: average \: speed = \frac{60}{ \frac{9}{4} } = \frac{60 \times 4}{9} \\ \\ \: \: \sf \implies \: average \: speed = 36.7 \frac{km}{hr}$

Hence,average speed of car is 36.7km/hr.

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