Question

A vehicle covers first half distance with
speed 20 kmph and other half distance with
speed 30 kmph. Then average speed​

Answer 1

Answer: 24 KM/H

Explanation:

Let the distance be 'x'

During first half:

Distance = x/2

speed = 20kmph

time = Distance/speed = (x/2)/20 = x/40

During second half:

Distance = x/2

speed = 30 kmph

time = Distance/speed = (x/2)/30 = x/60

Average speed = Total distance/total time taken = x/[(x/40)+(x/60)]

= 120x/5x

X = 24

Answer 2

Answer:

Average speed is 24km/hr

Explanation:

Let distance be 120 km

$\longrightarrow\tt Half \: of \: distance = \frac{120}{2} = 60 \: km \\ \\ \longrightarrow \tt Time \: taken \: in \: half \: distance = \frac{Distance}{Speed} = \frac{60}{20} = 3 \: hr \\ \\ \longrightarrow \: \tt \: Time \: taken \: in \: rest \: distance = \frac{60}{30} = 2 \: hr \\ \\ \implies \tt \:Average \: Speed = \frac{Total \: distance}{Total \: time \: taken} = \frac{120}{2 + 3} = \frac{120}{5} = \underline{ \underline{ \red{ \boxed{ \green{ \tt \: 24 \: }}}}}$