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 6 of 15.
Ali said:
6 years ago
10 hrs we can divide it as 5 + 5 hrs.
1st half of journey at rate of 21 km/hr,
So 21*5=105,
2nd half of journey at rate of 24 km/hr.
So 24*5 = 120.
105+120 = 225.
So option B 224 is correct.
1st half of journey at rate of 21 km/hr,
So 21*5=105,
2nd half of journey at rate of 24 km/hr.
So 24*5 = 120.
105+120 = 225.
So option B 224 is correct.
Vinay said:
6 years ago
Take Avg speed formule=2xy/x+y.
Substitute the values x=21, y=24.
Then you get the answer 22.4 its avg distance,
So multiplied with 10, because the time taken is 10 hours,
You get 224km.
Substitute the values x=21, y=24.
Then you get the answer 22.4 its avg distance,
So multiplied with 10, because the time taken is 10 hours,
You get 224km.
Sarika datir said:
2 decades ago
We can calculate it by using formula of avg speed also.
x=21,y=24
Formula of avg spped=2xy/x+y
=2(21*24)/21+24
=1008/45=22.4KM/hr
avg spped=22.4km/hr
distance=Speed* time=22.4*10=224km
x=21,y=24
Formula of avg spped=2xy/x+y
=2(21*24)/21+24
=1008/45=22.4KM/hr
avg spped=22.4km/hr
distance=Speed* time=22.4*10=224km
Diana said:
5 years ago
First half of the journey, means the first half of the distance to be travelled. Not, the first half of the time required to reach your destination! That's how it is 224 instead of 225.
(1)
Sid said:
1 decade ago
@Mohammed is wrong.
Because,
Average speed is the weighted average with the time traveled at the different speeds being the weight & not the distance traveled at different speeds.
Because,
Average speed is the weighted average with the time traveled at the different speeds being the weight & not the distance traveled at different speeds.
Vinod patil said:
5 years ago
1st half of distance d/2..
2nd half of distance d/2
Distance is constant.
1st half of journey + 2nd half of journey = Total time of journey.
(d/2)/21 +(d/2)/24 = 10.
d = 224kmph.
2nd half of distance d/2
Distance is constant.
1st half of journey + 2nd half of journey = Total time of journey.
(d/2)/21 +(d/2)/24 = 10.
d = 224kmph.
Francis K Joseph said:
1 year ago
Let's take a formula = 2XY/X + Y.
Here, X=21 and Y= 24.
so, the formula is = 2 * 21 * 24/21 + 24,
=1008/45.
Here, your Answer = 22.4 * 10 = 224.
Here, X=21 and Y= 24.
so, the formula is = 2 * 21 * 24/21 + 24,
=1008/45.
Here, your Answer = 22.4 * 10 = 224.
(22)
Mani Gupta said:
7 years ago
How this is possible that a train travels with 21 km/h speed and 24 km/h speed, covers same distance?
So, we have to assume different distance for a different speed. Right?
So, we have to assume different distance for a different speed. Right?
Kartik Arya said:
6 years ago
After,
x/21 + x/24 = 20.
Multiply equation with 3.
So you get,
x/7 + x/8 = 20*3.
So 15x/56=20*3.
Now :- x=20*3*56/15.
x=20*56/5.
x=4*56=224km.
x/21 + x/24 = 20.
Multiply equation with 3.
So you get,
x/7 + x/8 = 20*3.
So 15x/56=20*3.
Now :- x=20*3*56/15.
x=20*56/5.
x=4*56=224km.
Abhinav said:
1 decade ago
The best way to choose the answer.
Check the option and find the multiple of 21 (divisible by 7) and.
(b) is right because it's a divisble by 7 and also multiple of 21.
Check the option and find the multiple of 21 (divisible by 7) and.
(b) is right because it's a divisble by 7 and also multiple of 21.
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