A train covers the first 16 km at a speed of 20 km per hour another 20 km at 40 km per hour and the last 10 km at 15 km per hour. Find the average speed for the entire journey.
A. 24 km
B. 26 km
C. 21 km
D. \[23\frac{{23}}{{59}}\] km
Answer: Option D
Solution(By Examveda Team)
$$\eqalign{ & {\text{Average}}\,{\text{speed}} \cr & = \frac{{{\text{total}}\,{\text{distance}}\,{\text{covered}}}}{{{\text{total}}\,{\text{time}}}} \cr & {\text{Total}}\,{\text{Distance}} \cr & = {16 + 20 + 10} \cr & = 46\,{\text{km}} \cr & {\text{Time}}\,{\text{taken}} \cr & = {\frac{{16}}{{20}}} + {\frac{{20}}{{40}}} + {\frac{{10}}{{15}}} \cr & = {\frac{{4}}{{5}}} + {\frac{{1}}{{2}}} + {\frac{{2}}{{3}}} \cr & = {\frac{{24 + 15 + 20}}{{30}}} \cr & = \frac{{59}}{{30}} \cr & {\text{Average}}\,{\text{speed}} \cr & = \frac{{46 \times 30}}{{59}} \cr & = 23\frac{{23}}{{59}}\,{\text{km/hr}} \cr} $$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
1st journey :-
Distance = 16 km.
speed = 20 km/hr .
Time = Distance/speed .
16/20 = 4/5 hrs
▶ 2nd journey :-
Distance = 20 km.
speed = 40 km/hr.
Time = Distance/Speed
20/40 =1/2 hrs
▶3rd journey :-
Distance = 10 km.
Time = 15 km/hr .
Time = Distance/Speed
10/15 =2/5
➡ Now,
avrg= total distance travelled/total time =2323/59
How it is 24+15+20/30 arrived
Can you explain please
We have 16/20+20/40+10/15 as given in the question now by calculating this we get 4/5+1/2+2/3
After this for 4/5we multiply it with the bottom numbers 2 and also from 3 we get 4*2*3i.e24
So 24/5 next for 1/2 we multiply it with the bottom numbers 5and 3i. e, 5*3*1=15 so 15/2 and DJ or 2/3 we multiply it with the bottom numbers 5and 2 I. e, 20/3 now multiply all the bottom numbers I. e, 5*2*3=30 so atlast we get the answer 24+15+20/30
By adding 24+15+30 we get 59 which is divided by 30 hence we get 59/30
How 24+15+20/30 arrived
How this 59/30
16+40+10=46? How you add this
23(60/59)
Can some one help in understanding how 59 is arrived?
Average speed = 46*30/59 = 23(23/59) km/hr.
???????????????
how 46*30/59 = 23(23/59) ????
Can you please explain?
Why we 120 km
16+20+10=46#