One-fourth of certain journey is covered at the rate of 25 km/h, one-third at the rate of 30 km/h and the rest at 50 km/h. Find the average speed for the whole journey.
$\text{ A. } \frac{600}{53} \mathrm{~km} / \mathrm{h}$
$\text{ C. } \frac{1800}{53} \mathrm{~km} / \mathrm{h}$
Show Answer
Answer-C
Solution-
Solution(By Apex Team)
Let distance be 120 km Hence 30 km is covered by @25 kmph and 40 km covered by @30 kmph and rest 50 km has been covered @50 kmph
Now,
$\begin{array}{l}\text{ average }=\Large\frac{120}{\text{ total time taken }}\\
=\Large\frac{120}{\frac{30}{25}+\frac{40}{30}+\frac{50}{50}}\\
=\Large\frac{3600}{106}\\
=\Large\frac{1800}{53}\mathrm{~km}/\mathrm{h}\end{array}$
