Question

Q 6/60 A car is moving on a straight road covers one
third of the total distance with speed 25 km/h
and rest with speed of 50 km/h. The average speed of
the car is​

Answer 1

Hey friend!

Here is your answer:

Let the total distance of the journey be x km.

Given,

Speed taken in the first ˣ/₃ km distance = 25 km/h

Speed taken in the next ( x - ˣ/₃ ) km distance = 50 km/h

We know, time = $\frac{distance}{speed}$

Time taken in the first ˣ/₃ km distance = ˣ/₃ ÷ 25

                                                           = ˣ/₇₅ h

Again,

Time taken in the next ²ˣ/₃ distance = ²ˣ/₃ ÷ 50

                                                       = ˣ/₇₅ h

Now,

Average speed = total distance ÷ total time

                        = x ÷ (ˣ/₇₅ + ˣ/₇₅)

                        = x ÷ (²ˣ/₇₅)

                        = 75/2 km/h

                        = 37.5 km/h

Answer: Average speed = 37.5 km/h

I hope it helps you and if you like my answer, please don't forget to respond with your thanks.....

Answer 2

$\sf\large\underline{Given:}$

• $\sf{A\:car\: covers\:1/3\:of total\:distance\: with\:speed\:of\:25km/h}$
• $\sf{Rest\: distance\: covers\:with\:the\: speed\:of\:50km/h}$

$\sf\large\underline{To\: Find:}$

• $\sf{The\: average\: speed\:of\:the\:car=?}$

$\sf\large\underline{Solution:}$

• [At first calculate the time here]

$\sf{\implies Let,\:The\: total\: distance\: covered\:by\:car\:be\:xkm}$

$\rm{\implies Time=\dfrac{Distance}{speed}}$

• [Total time taken in the 1st state]

$\rm{\implies Time=\dfrac{x}{3}\div 25}$

$\rm{\implies Time=\dfrac{x}{75}}$

• [Total time taken in the 2nd state]

$\rm{\implies Time=(x-\dfrac{x}{3})\div 50}$

$\rm{\implies Time=\dfrac{2x}{3}\div 50}$

$\rm{\implies Time=\dfrac{2x}{150}}$

• [Now, calculate avarage speed of the car]

$\rm{\implies Avarage\: speed=\dfrac{Total\: distance}{Total\:time}}$

$\rm{\implies Avarage\: speed=x\div (\dfrac{x}{75}+\dfrac{2x}{150})}$

$\rm{\implies Avarage\: speed=x\div (\dfrac{2x+2x}{150})}$

$\rm{\implies Avarage\: speed=x*\dfrac{150}{4x}}$

$\rm{\implies Avarage\: speed=\dfrac{150x}{4x}}$

$\rm{\implies Avarage\: speed=\dfrac{75}{2}}$

$\rm{\implies Avarage\: speed=37.5km/h}$

Hence,

$\rm\purple{\implies The\: avarage\: speed\:of\:the\:car\:is\:37.5km/h}$