Question

Revisit
A Tempo travels at a certain average speed for a distance of 60 km and then travels a distance
of 90 km at an average speed of 15 kmph. If it takes 8 hours to complete the total journey, find
its initial average speed.​

Answer 1

$\huge \purple{ \underbrace{ \orange {\underbrace{ \green{\overbrace{Answer}}}}}}$

$\huge \bold{ \underline{Given,}}$

$\bold{Distance \: travel \: by \: tempo = 60km}$

$\bold{Time \: taken = 2 hrs}$

$\bold{speed = \frac{distance}{time} }$

$\bold{ = \frac{60}{2} }$

$\bold{= 30 km /hr}$

$\bold{distance \: travel \: by \: car = 80 km}$

$\bold{time \: taken = 1hr}$

$\bold{speed = \frac{distance}{time} }$

$\bold{ = \frac{ 80}{1} }$

$\bold{= 80 km/hr}$

$\bold{ratio \: of \: their \: speed = \frac{30}{80} }$

$\bold{ = \frac{3}{8} }$

$\bold{= 3:8}$

Answer 2

Answer:

The average speed of the initial journey is 30kmph.

Step-by-step explanation:

Given the distance of first part of journey, $d_{1} =60 km$

The distance of second part of journey, $d_{2} =90 km$

Average speed of second part of journey,  $s_{2} =15 kmph.$

Total time of journey, $t=8 hours$

Speed is defined as distance travelled per unit time, i.e., $s=\frac{d}{t}$

Then time can be written as $t=\frac{d}{s}$

And the total time for the journey is

$t=\frac{d_{1} }{s_{1}}+\frac{d_{2 }}{s_{2}}}$

Substituting the values,

$8=\frac{60}{s_{1}}+\frac{90}{15}$

$\implies 8=\frac{60}{s_{1}}+6$

$\implies 2=\frac{60}{s_{1}}$

$\implies {s_{1}}=\frac{60}{2}=30kmph$

Therefore the average speed of the initial journey is 30kmph.