Suppose you walk from home to the bus stand at 4 km - h and immediately return at x km - h- If the average speed is 6 km - h then x isA- 8 km - hB- 10 km - hC- 12 km - hD- Cannot be determined unless the distance from home to bus stand is known-

A bus travels the first one-third distance at a speed of 10 $\frac{k m}{h}$ , the next one-third at 20 $\frac{k m}{h}$ and the last one-third at 60 $\frac{k m}{h}$ . The average speed of the bus is

If you are walking at constant velocity of 8 km/h and a car passed you by at the speed of 20

km/h from behind, what is the car's velocity from your viewpoint?

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Suppose you walk from home to the bus stand at 4 km/h and immediately return at x km/h. If the average speed is 6 km/h then x is

The correct option is C 12 km/h 6=2SS4+Sx ⇒3=4xx+4 ⇒3x+12=4x ⇒x=12km/h

The correct option is C
12 km/h

$6 = \frac{2 S}{\frac{S}{4} + \frac{S}{x}}$

$\Rightarrow 3 = \frac{4 x}{x + 4}$

$\Rightarrow 3 x + 12 = 4 x$

$\Rightarrow x = 12 k m / h$