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 1 of 15.
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)
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)
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)
Nithin said:
9 months ago
The right answer is 234 km.
(4)
Ansh Raghav said:
11 months ago
@ALL.
According to the given question;
x/21 + x/24 =10
15x/168 = 10.
By cross multiplication;
168 × 10 = 15x.
1680 = 15x.
122 = x.
2x = 224.
According to the given question;
x/21 + x/24 =10
15x/168 = 10.
By cross multiplication;
168 × 10 = 15x.
1680 = 15x.
122 = x.
2x = 224.
(24)
Himanshu said:
12 months ago
Let the Distance = 2x.
So, By Formula T = D/S.
The distance covered by each = x.
10 = x/21+x/24,
5040 = 45x,
X = 122.
So Distance =2x,
= 2x122,
=224 Km.
So, By Formula T = D/S.
The distance covered by each = x.
10 = x/21+x/24,
5040 = 45x,
X = 122.
So Distance =2x,
= 2x122,
=224 Km.
(21)
Gowthaman 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.
(32)
Hardik H Bagaria said:
1 year ago
@All.
For the people who got an answer as 225km, we cannot assume that the time taken to complete half of the journey (distance) is 5hrs, assuming 5hrs for the first trip and 5 for the second is wrong.
Because its not relative to the time, but rather relative to the journey (distance).
For the people who got an answer as 225km, we cannot assume that the time taken to complete half of the journey (distance) is 5hrs, assuming 5hrs for the first trip and 5 for the second is wrong.
Because its not relative to the time, but rather relative to the journey (distance).
(49)
Pradumn said:
1 year ago
By using the formula = 2xy/x + y.
= 2 * 21 * 24/21 + 24.
= 1008/45,
= 22.4,
= 22.4 * 10.
= 224km.
= 2 * 21 * 24/21 + 24.
= 1008/45,
= 22.4,
= 22.4 * 10.
= 224km.
(35)
Francis K Joseph said:
2 years 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)
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