A car covers its outward journey at 40kmph. It is towed back, over exactly the same distance at 10mph. What is the average speed over the entire journey? A)12mph B)14mph C)15mph D)20mph
SUDHARSANA V V , 6 Years ago
Grade 10
3 Answers
Arun
Last Activity: 6 Years ago
Dear student
we can apply the formula 2xy/(x+y) for average speed.
Hence
Avg speed = 2*40*10/(40+10) = 800/50 = 16 kmph
Regards
Arun (askIITians forum expert)
SUDHARSANA V V
Last Activity: 6 Years ago
Before working out Km is to be converted in to miles isn`t it. Hence 40km isto be converted and then average speed to be found out.
Arun
Last Activity: 6 Years ago
Sorry, thanks for pointing it out.
40 kmph = 40/1.6 mph = 24.85 mph
Now avg speed = 2*24.85*10/34.85 = 14.26 mph
Hence option B is correct
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