Aptitude - Time and Distance - Discussion
Discussion Forum : Time and Distance - General Questions (Q.No. 7)
7.
A man complete a journey in 10 hours. He travels first half of the journey at the rate of 21 km/hr and second half at the rate of 24 km/hr. Find the total journey in km.
Answer: Option
Explanation:
| (1/2)x | + | (1/2)x | = 10 |
| 21 | 24 |
 |
x | + | x | = 20 |
| 21 | 24 |
15x = 168 x 20
| x = |
 |
168 x 20 |  |
= 224 km. |
| 15 |
Discussion:
141 comments Page 5 of 15.
Ankit kumar Jha said:
9 years ago
According to me,
It is clear that first half hour the speed is 21 so total distance would be 21 * 5 = 105 km
And in second-hour distance would be 24 * 5 = 120 km,
So, the Total distance be 105 + 120 = 225 km.
It is clear that first half hour the speed is 21 so total distance would be 21 * 5 = 105 km
And in second-hour distance would be 24 * 5 = 120 km,
So, the Total distance be 105 + 120 = 225 km.
Maya said:
8 years ago
For these kind ques, there is a simple formula i.e.
Distance= 2* time* product of speeds / addition of speeds
ans: distance = 2*10*21*24 /21+24.
=10080/45,
= 224 km.
Distance= 2* time* product of speeds / addition of speeds
ans: distance = 2*10*21*24 /21+24.
=10080/45,
= 224 km.
Amit said:
1 decade ago
We know that when dist travlled is equal the its harmonic mean so,
we can get by => avg speed*time= dist
=2(21*24)/21+24
=1008/45=22.4KM/hr
avg speed=22.4km/hr
Distance = Speed* time = 22.4*10 = 224 km.
we can get by => avg speed*time= dist
=2(21*24)/21+24
=1008/45=22.4KM/hr
avg speed=22.4km/hr
Distance = Speed* time = 22.4*10 = 224 km.
Sakthivel said:
10 years ago
First half of the journey is 21 km, 24 km.
Average speed during 21 km, 24 km = 2xy/x+y.
= 2 (21*24) /21+24.
= 1008/45 = 112/5.
He complete the hole journey in 10 hrs.
So, 112/5*10 = 224.
Thank you!
Average speed during 21 km, 24 km = 2xy/x+y.
= 2 (21*24) /21+24.
= 1008/45 = 112/5.
He complete the hole journey in 10 hrs.
So, 112/5*10 = 224.
Thank you!
Parkavi said:
5 years ago
Average speed = 2xy/x+y.
Here
X =21.
Y = 24.
Then, the average speed is;
2(21)(24)/45 = 22.4.
Average speed= total distance/total time.
22.4 = X/10,
224 = X,
Finally, the distance is 224.
Here
X =21.
Y = 24.
Then, the average speed is;
2(21)(24)/45 = 22.4.
Average speed= total distance/total time.
22.4 = X/10,
224 = X,
Finally, the distance is 224.
(2)
Surender said:
8 years ago
First half hour the speed is 21 so total distance would be 21 * 5 = 105 km,
And in second-hour distance would be 24 * 5 = 120 km,
So, the Total distance be 105 + 120 = 225 km.
Why this is not correct?
And in second-hour distance would be 24 * 5 = 120 km,
So, the Total distance be 105 + 120 = 225 km.
Why this is not correct?
MALLIKARJUN said:
1 decade ago
Simple trick.
Find average speed because they are given half and half journey.
2xy/x+y......> 2(21)(24)/(21+24).
So average speed = 2(21)(24)/45.
Therefore D = S*T.
= [2(21)(24)/45]*10 = 224.
Find average speed because they are given half and half journey.
2xy/x+y......> 2(21)(24)/(21+24).
So average speed = 2(21)(24)/45.
Therefore D = S*T.
= [2(21)(24)/45]*10 = 224.
Manhar said:
1 decade ago
Hi @Vikash.
Let the total distance = X (becoz we don't know the total distance or journey).
So, 1st half means X/2, 2nd half means also X/2.
That's why we can multiplied with(1/2) in first step.
Let the total distance = X (becoz we don't know the total distance or journey).
So, 1st half means X/2, 2nd half means also X/2.
That's why we can multiplied with(1/2) in first step.
Muhammad Umair Kabir said:
1 decade ago
Distance = (Speed x Time).
First five hours speed was 21 km/ h
So D1 = 21 * 5 = 105
Next five hours speed was 24 km / h
D2 = 24 * 5 = 120
ADD them 225 km / h which is nearer to 224 km / h
First five hours speed was 21 km/ h
So D1 = 21 * 5 = 105
Next five hours speed was 24 km / h
D2 = 24 * 5 = 120
ADD them 225 km / h which is nearer to 224 km / h
Dave said:
1 decade ago
How is @Muhammed way incorrect? that what I did it close but if this was not a multiple choice it would be wrong so can anyone explain it to me. When I mean explain like dumb it right down please.
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers