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 10 of 15.
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.
Pavan V D said:
1 decade ago
(1/2)x/21+(1/2)x/24 = 10.
x/21+x/24 = 20.
Take LCM,
45x/504 = 20.
x/11.2 = 20.
x = 224.0km.
x/21+x/24 = 20.
Take LCM,
45x/504 = 20.
x/11.2 = 20.
x = 224.0km.
Abhishek said:
1 decade ago
(x/21)+(x/24)=20;
taking LCM,we get-
(45x/504)=20;
and 45/504=15/168;
so 15x=168*20;
x=224;
taking LCM,we get-
(45x/504)=20;
and 45/504=15/168;
so 15x=168*20;
x=224;
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.
Subham said:
9 years ago
d = (2 * T * x * y)/(x + y) formula can also be used where x and y are two different speed.
Abhik said:
1 decade ago
Avg speed = 2xy/x+y = 2.21.24/(21+24)= 112/5
distance= speed * tym = 112/5 * 10 = 224....
distance= speed * tym = 112/5 * 10 = 224....
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.
Mohit said:
1 decade ago
Can't we solve like this:
21*5=105 and 24*5=5 which equal to 225 instead of 224 why?
21*5=105 and 24*5=5 which equal to 225 instead of 224 why?
Chandan pal said:
1 decade ago
Avg speed: 2xy/x+y.
Avg speed: 2*21*24/21+24 = 112/5.
Distance = (112/5)*10 = 224.
Avg speed: 2*21*24/21+24 = 112/5.
Distance = (112/5)*10 = 224.
Bhavin said:
3 years ago
x/21 + x/24 = 20.
24x + 21x = 20* 21 *24,
45x = 10,080,
x =10,080/45.
Ans x = 224.
24x + 21x = 20* 21 *24,
45x = 10,080,
x =10,080/45.
Ans x = 224.
(8)
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