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.
A. $$\frac{{600}}{{53}}$$ km/h
B. $$\frac{{1200}}{{53}}$$ km/h
C. $$\frac{{1800}}{{53}}$$ km/h
D. $$\frac{{1600}}{{53}}$$ km/h
E. None of these
Answer: Option C
Solution(By Examveda 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 kmphNow,
$$\eqalign{ & {\text{average}} = {\frac{{120}}{{{\text{total}}\,{\text{time}}\,{\text{taken}}}}} \cr & = \frac{{120}}{{\frac{{30}}{{25}} + \frac{{40}}{{30}} + \frac{{50}}{{50}}}} \cr & = \frac{{3600}}{{106}} \cr & = \frac{{1800}}{{53}}\,{\text{km/h}} \cr} $$
This Question Belongs to Arithmetic Ability >> Average
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Comments ( 11 )
Related Questions on Average
A. 125 km/hr
B. 75 km/hr
C. 135 km/hr
D. 120 km/hr
Enna ninte achantel konden kodukkada , bruu that’s myre
Any short trick
1/4+1/3=7/12
Remaining 1-(7/12)=50
5x/12=50
X=120
consider:
x/4/25 +x/3/30 + 5x/12/50(where 12=4*3)
then:
we get, x/100+x/90+x/120
=18x+20x+15x/1800
+53x/1800
so,to find average speed for whole journey is,
x/53x/1800
=1800x/53x
=1800/53
easyyy lmao
he as assumed the total distance as 120. Assuming 120 makes it easy to divide the number into 1/3rd , 1/4th and the rest. For example if you assume the distance to be 100, on dividing you get the distance in decimal point which makes it difficult to calculate. Hence 120.
How did you get total of 120
First two distance and speed total
30+25+40+90=120
Its easy guys! 1/3 1/4 and the rest
So you take a number which will be divisible by 3 , 4 and 1 .
Which is 12
And we need it in Kms so we take 120 instead
How did you let total distance as 120 km..??
How did you get total distance as 120