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:
143 comments Page 15 of 15.
VISHNU said:
4 months ago
Time = 10hr.
Speed = 21 and 24, 21 + 24 = 45.
Distance = speed * time.
Distance = 10*45 = 450.
The journey is 2 parts.
450/2 = 225 ~224.
Speed = 21 and 24, 21 + 24 = 45.
Distance = speed * time.
Distance = 10*45 = 450.
The journey is 2 parts.
450/2 = 225 ~224.
(22)
Subha said:
2 months ago
Let the time for 1st half be x.
x.21 = (10-x).24
x = 80/15.
D = 80/15 X 21 X2
= 224km.
x.21 = (10-x).24
x = 80/15.
D = 80/15 X 21 X2
= 224km.
(5)
Dish said:
3 weeks ago
Why can't the answer be calculated like average speed?
We sum up the speeds of 21 and 24, divide by 2, and use that speed in the formula.
Multiply 10 hours by 22.5 kmph and get 225 km!
@All.
Here I got a different answer. I am not getting it clearly. So, can anyone clarify this to me?
We sum up the speeds of 21 and 24, divide by 2, and use that speed in the formula.
Multiply 10 hours by 22.5 kmph and get 225 km!
@All.
Here I got a different answer. I am not getting it clearly. So, can anyone clarify this to me?
(2)
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