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 11 of 15.
Niraj said:
6 years ago
@Niraj :STEP 1:- there will come divide(/) at the pace of multiple (x) I did mistake here so it will come in,
Step 1: x(1/2) /21 + x(1/2)/ 24 = 10.
Step 1: x(1/2) /21 + x(1/2)/ 24 = 10.
Uma shankari said:
6 years ago
Avg spd- 2*21*24/ 45 (avg spd- 2xy/x+y).
Time - 10h.
D = s*t.
Just multiply both.
This will be easy.
Time - 10h.
D = s*t.
Just multiply both.
This will be easy.
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:
5 years ago
2x21x24 = 1008÷10 = 224.
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)
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.
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.
(1)
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