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 8 of 15.
Sri said:
1 decade ago
USE FORMULA :
Suppose a man covers a certain distance at x km/hr and an equal distance at y km/hr. Then,
The average speed during the whole journey is,
= 2(X)(Y)/(X)+(Y).
= 2(21)(24)/21+24.
= 1008/45.
= 22.4KM (AVERAGE SPEED).
NOW WE KNOW THE SPEED, SO SPEED = DISTANCE/TIME.
22.4 = DISTANCE/10 (MULTIPLYING 22.4 * 10 WE GET 224)
224 KMS.
Suppose a man covers a certain distance at x km/hr and an equal distance at y km/hr. Then,
The average speed during the whole journey is,
= 2(X)(Y)/(X)+(Y).
= 2(21)(24)/21+24.
= 1008/45.
= 22.4KM (AVERAGE SPEED).
NOW WE KNOW THE SPEED, SO SPEED = DISTANCE/TIME.
22.4 = DISTANCE/10 (MULTIPLYING 22.4 * 10 WE GET 224)
224 KMS.
GHUHI said:
1 decade ago
5*21 = 105 KM.
5*24(KM/HR) = 120 KM.
SO TOTAL DISTANCE TRAVEL.
105+120 = 225.
5*24(KM/HR) = 120 KM.
SO TOTAL DISTANCE TRAVEL.
105+120 = 225.
Ketaki said:
1 decade ago
If any object does journey in 'T' hours the 1st half at a km/hr and 2nd half at b km/hr the total distance is :(2*T*a*b)/(a+b).
Sakpal poonam said:
1 decade ago
Total average speed = (2*24*21)/(21+24).
Speed = 1008/45.
Distance = speed/time.
= (1008/45)/10.
= 224 km.
Speed = 1008/45.
Distance = speed/time.
= (1008/45)/10.
= 224 km.
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.
Kavitha said:
1 decade ago
How you got LCM as 45x/105?
Sajan said:
1 decade ago
Simple formula is 2t(s1*s2)/s1+s2.
So, 2*10(21*24)/21+24.
= 20*504/45.
= 20*11.2.
= 224.
So, 2*10(21*24)/21+24.
= 20*504/45.
= 20*11.2.
= 224.
Ranjitha said:
1 decade ago
How you get 20?
Ab rahuman said:
1 decade ago
Use average speed formula 2xy/x+y and multiply with time.
Since Distance = Time*Speed.
Since Distance = Time*Speed.
Gayu said:
1 decade ago
I can't understand this problem. Please explain.
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