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 14 of 15.
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.
Sudarshan said:
6 years ago
The formula to find avg speed is;
Avg speed= 2(s1)(s2)/(s1+s2).
where s1 and s2 are speeds
On calculating, the avg speed comes out to be 112/5.
Now to find the distance, we have a formula i.e, distance = speed x time.
Distance = (112/5) x 10 = 224km.
Avg speed= 2(s1)(s2)/(s1+s2).
where s1 and s2 are speeds
On calculating, the avg speed comes out to be 112/5.
Now to find the distance, we have a formula i.e, distance = speed x time.
Distance = (112/5) x 10 = 224km.
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.
Aryan said:
6 years ago
2x21x24 = 1008÷10 = 224.
Sourabh said:
5 years ago
How came 20? Explain me.
Anmol DHAWAN said:
5 years ago
Why have you taken x/2 for both terms?
From my point of view, x/2 in the first and x in the second term.
From my point of view, x/2 in the first and x in the second term.
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.
Hardik Maheshwari said:
5 years ago
I think the ans should be 225 because in first half mean in 5km he covered distance at a speed of 21kmph.
=21 * 5=105.
And in second half it mean 5km he covered distance at a speed of 24kmph =24 * 5=120.
By adding both distance=105 + 120 = 225.
Hence the ans should be 225.
=21 * 5=105.
And in second half it mean 5km he covered distance at a speed of 24kmph =24 * 5=120.
By adding both distance=105 + 120 = 225.
Hence the ans should be 225.
Muskan said:
5 years ago
AVG.speed=2v1*v2/V1+V2
= 2*21*24/21+24
=22.4km/h.
Distance = speed * time.
=22.4 *10
= 224km.
= 2*21*24/21+24
=22.4km/h.
Distance = speed * time.
=22.4 *10
= 224km.
Charan said:
5 years ago
Let, distance be 'x'
The for the first half, distance = x * 1/2.
For the second half also, distance = x * 1/2.
Then , time = distance/speed.
Therefore, time taken for first half = (x*1/2)/21 = x/42.
Time taken for second half = (x*1/2)24 = x/48.
Therefor total time = x/42 +x/48 and that is given as 10 minutes.
So, x/42+x/48 = 10.
Solving this, you get (48x + 42x) = 48*42*10.
On solving , 90x = 48*42*10.
We get x = 224.
The for the first half, distance = x * 1/2.
For the second half also, distance = x * 1/2.
Then , time = distance/speed.
Therefore, time taken for first half = (x*1/2)/21 = x/42.
Time taken for second half = (x*1/2)24 = x/48.
Therefor total time = x/42 +x/48 and that is given as 10 minutes.
So, x/42+x/48 = 10.
Solving this, you get (48x + 42x) = 48*42*10.
On solving , 90x = 48*42*10.
We get x = 224.
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