Question

hii please solve the problem

Answer 1

[0010001111]... Hello User... [1001010101]
Here's your answer...

Speed = Distance/Time
Time = Distance/Speed

Avg. speed = Total distance/Total time

For first part of the journey,
Distance = 30 km
Speed = 30 km/hr
Time = 30/30 = 1 hour

For the second part of the journey,
Distance = 30 km
Speed = 60 km/hr
Time = 30/60 = 0.5 hour

Avg. Speed
$= \frac{30 + 30}{1 + 0.5} \\ = \frac{60}{1.5} \\ = \frac{600}{15} \\ = 40$
The average speed of the journey will be 40 km/hr.

Here's a little hint for you.
When there is this type of question, and the distance covered is equal, avg. speed will be...
$\frac{2 \times v1 \times v2}{v1 + v2}$
Where v1 and v2 are the two velocities given in the question.

If time is equal, then the formula will be...
$\frac{v1 + v2}{2}$

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Answer 2

Your answer is option c: 40km/h


Average speed = total distance/total time taken


average speed= 60km/1.5h

average speed = 40km/h(ans.)