Question : During a journey, a person travels half of the distance at a speed of 18 km/h and the remaining half of the journey at a speed of 22 km/h. What is his average speed for the entire journey?
Option 1: 21.4 km/h
Option 2: 20.2 km/h
Option 3: 19.2 km/h
Option 4: 19.8 km/h
Correct Answer: 19.8 km/h
Solution :
Let $d$ be the total distance of the journey.
Half of the distance at 18 km/h and the remaining half at 22 km/h
⇒ Total Time for the journey = $\frac{d}{2×18}$ +$\frac{d}{2×22}$
⇒ average Speed = $\frac{\text{d}}{\text{$\frac{d}{2×18}$ +$\frac{d}{2×22}$ }}$ = $\frac{\text{d}}{\text{$\frac{22d}{2×18×22}$ +$\frac{18d}{2×18×22}$ }}$ = $\frac{d}{\frac{40d}{2×18×22}}$
= $\frac{18×22}{20}$
= 19.8
Hence, the correct answer is 19.8 km/h.
Related Questions
Know More about
Staff Selection Commission Multi Tasking ...
Application | Cutoff | Selection Process | Preparation Tips | Eligibility | Exam Pattern | Admit Card
Get Updates Brochure
Your Staff Selection Commission Multi Tasking Staff Exam brochure has been successfully mailed to your registered email id “”.
