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 9 of 15.
Velu said:
1 decade ago
There said half the journey. So why didn't we get half the time for calculation.
Like (5*24)+(5*21) = 225.
Like (5*24)+(5*21) = 225.
Suresh Mahiya said:
1 decade ago
Average speed = 2*21*24/21+24.
= 22.4km/hr.
So Total Journey will be = speed * time.
= 22.4*10.
224 km.
= 22.4km/hr.
So Total Journey will be = speed * time.
= 22.4*10.
224 km.
Rajat said:
8 years ago
Average Speed={(2XY)/(X+Y)}.
= {(2*21*24)/(21+24))
= 112/5 km/hr.
Distance=Speed*time=(112/5)*10=224 KM.
= {(2*21*24)/(21+24))
= 112/5 km/hr.
Distance=Speed*time=(112/5)*10=224 KM.
Rajesh said:
8 years ago
Distance =speed*time.
So x=(21*5)+(24*5)=225.
X=225 km.
Why should it not be like this? Please explain.
So x=(21*5)+(24*5)=225.
X=225 km.
Why should it not be like this? Please explain.
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.
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.
Sridhar said:
9 years ago
We should not take average speed, in this case, it is clearly mentioned that 1st half and 2nd half.
Sivaprakash said:
3 years ago
It may easily be by using averages for 10 hrs- (5*21)+(24*5) = 22.5.
And D = S*T.
22.5 * 10 = 225km
And D = S*T.
22.5 * 10 = 225km
(30)
Sandeep kumar said:
1 decade ago
First half of journey means half distance of journey. Not half ours of time. May it will help you.
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.
(33)
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