A car during its journey travels 30 minutes at a speed of 40km/hr, another 45 minutes at a speed of 60 km/hr, and 2 hours at a speed of 70 km/hr average speed of the car is

63 km/hr

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65 km/hr

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70km/hr

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None of these

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Solution

The correct option is A 63 km/hr
(a)
Here,
$T_{1} = \frac{30}{60}, T_{2} = \frac{30}{60}, T_{3} = 2, s_{1} = 40$

$s_{2} = 60 a n d s_{3} = 70$

$= \frac{s_{1} T_{1} + s_{2} T_{2} + s_{3} T_{3}}{T_{1} + T_{2} + T_{3}}$

$= \frac{40 \times \frac{30}{60} + 60 \frac{45}{60} + 70 \times 2}{\frac{30}{60} + \frac{45}{60} + 2}$

= 63 km/hr

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