Sequence And Series Question 272
Question: A boy goes to school from his home at a speed of x km/hour and comes back at a speed of y km/hour, then the average speed is given by
[DCE 2002]
Options:
A) A.M.
B) G.M.
C) H.M.
D) None of these
Show Answer
Answer:
Correct Answer: C
Solution:
Let, the distance of school from home = d and time taken are $ t_1 $ and t2.
$ \therefore t_1=\frac{d}{x} $ and $ t_2=\frac{d}{y} $ Avg. velocity = $ \frac{Total,distance}{Total,time} $ $ =\frac{2d}{( \frac{d}{x}+\frac{d}{y} )}=\frac{2xy}{x+y} $ , which is the H.M. of x and y.
BETA
