Aptitude - Races and Games - Discussion
Discussion Forum : Races and Games - General Questions (Q.No. 3)
3.
In a 500 m race, the ratio of the speeds of two contestants A and B is 3 : 4. A has a start of 140 m. Then, A wins by:
Answer: Option
Explanation:
To reach the winning post A will have to cover a distance of (500 - 140)m, i.e., 360 m.
While A covers 3 m, B covers 4 m.
| While A covers 360 m, B covers |  |
4 | x 360 |  m |
= 480 m. |
| 3 |
Thus, when A reaches the winning post, B covers 480 m and therefore remains 20 m behind.
A wins by 20 m.
Discussion:
14 comments Page 1 of 2.
Kriti said:
1 decade ago
Hi, when 3:4 is the ratio of speeds how can we use it
as 3m and 4m for A and B resp.?
as 3m and 4m for A and B resp.?
Sudheer said:
1 decade ago
Hi kriti here speed and distance are directly proportinal. If his speed is 10km/hr he cover 10km distance. If speed is 20km/hr he can cover 20 km distance. Thus speed and distance are directly proportinal. So here distance ratios also become3:4. But the time ratio will become4:3 because time and speed are inversly proportinal.
Vamsi said:
1 decade ago
I didn't understand how it can be 4/3. ?
Malli said:
1 decade ago
Hai, my dout is same that of vamsi.
Why we had taken 4/3 in problem?
Why we had taken 4/3 in problem?
Manojit said:
1 decade ago
While A covers 3 m, B covers 4 m.
While A covers 1m, B covers 4/3 m.
While A covers 360 m, B covers (4/3* 360)m =480 m.
Here time is same in case of speed.we count different distance in same time.
While A covers 1m, B covers 4/3 m.
While A covers 360 m, B covers (4/3* 360)m =480 m.
Here time is same in case of speed.we count different distance in same time.
Rajesh said:
1 decade ago
Can be solved by simple calculation.
A covers 360m (ie) 500-140.
Ratio of speeds of A:B = 3:4.
Let us consider A covers 3m/sec & B covers 4m/sec.
Time taken by A to cover 360m=(360/3)=120seconds.
So,Distance covered by B in 120s =120*4=480m.
Therefore,A wins by 20 metres which is (500-480).
A covers 360m (ie) 500-140.
Ratio of speeds of A:B = 3:4.
Let us consider A covers 3m/sec & B covers 4m/sec.
Time taken by A to cover 360m=(360/3)=120seconds.
So,Distance covered by B in 120s =120*4=480m.
Therefore,A wins by 20 metres which is (500-480).
Srinu said:
1 decade ago
Time = dis\speed.
T = 360\3 = 120sec.
Now dis = sxT = 4x120 = 480m.
So 500-480 = 20m.
This is the answer.
T = 360\3 = 120sec.
Now dis = sxT = 4x120 = 480m.
So 500-480 = 20m.
This is the answer.
Newstein Faraday . said:
1 decade ago
A has to travel 360 meters therefore Time =distance/ speed. So 360/3 = 120 seconds.
The same 120 seconds b has to travel so distance = speed x time = 4 x 120 = 480.
The remaining distance that b has to travel is 500-480 = 20.
The same 120 seconds b has to travel so distance = speed x time = 4 x 120 = 480.
The remaining distance that b has to travel is 500-480 = 20.
(1)
Damini.arora said:
1 decade ago
Here, because A has a start of 140, he has already covered 140 m when B starts. So when A covers rest of 360, B covers 480.
Hence B loses race by 20 m.
Hence B loses race by 20 m.
Ash said:
10 years ago
Speed is directly proportional to distance.
3/4 = (500-140)/(500-x).
3/4 = 360/(500-x).
Hence x = 20.
3/4 = (500-140)/(500-x).
3/4 = 360/(500-x).
Hence x = 20.
(1)
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