Question : If a boat goes upstream at a speed of 21 km/hr and comes back the same distance at 28 km/hr, what is the average speed (in km/hr) for the total journey?
Option 1: 24.5
Option 2: 24
Option 3: 25
Option 4: 25.4
Correct Answer: 24
Solution :
Given: Upstream speed of boat = 21 km/hr
Downstream speed of boat = 28 km/hr
For the same distance,
Average speed = $\frac{2ab}{a+b}$ where $a$ = 21 km/hr and $b$ = 28 km/hr
So, the average speed = $\frac{2\times 21\times 28}{21+28}$ = 24 km/hr
Hence, the correct answer is 24.
Related Questions
Know More about
Staff Selection Commission Combined Grad ...
Result | Eligibility | Application | Selection Process | Preparation Tips | Admit Card | Answer Key
Get Updates Brochure
Your Staff Selection Commission Combined Graduate Level Exam brochure has been successfully mailed to your registered email id “”.
Upcoming Exams
Trending Articles around SSC CGL
