Aptitude - Races and Games - Discussion
Discussion Forum : Races and Games - General Questions (Q.No. 2)
2.
A and B take part in 100 m race. A runs at 5 kmph. A gives B a start of 8 m and still beats him by 8 seconds. The speed of B is:
Answer: Option
Explanation:
| A's speed = |  |
5 x | 5 |  m/sec |
= | 25 | m/sec. |
| 18 | 18 |
| Time taken by A to cover 100 m = | |
100 x | 18 | sec |
= 72 sec. |
| 25 |
Time taken by B to cover 92 m = (72 + 8) = 80 sec.
| B's speed = |
|
92 | x | 18 | kmph |
= 4.14 kmph. |
| 80 | 5 |
Discussion:
29 comments Page 1 of 3.
Faizal khan said:
2 years ago
@Ramanjaneyulu.
Multiplying by 5/18, you can convert km/h to m/s.
Multiplying by 5/18, you can convert km/h to m/s.
(4)
Ramanjaneyulu said:
3 years ago
How 5/8 came? please explain me.
(1)
Anusha said:
4 years ago
Nice explanation, thanks @Buddhika.
Manikanta said:
5 years ago
Here A runs for 100meters while B has to run only for 92Meters as B is 8meters ahead of A.
5km per hour=5000 meters per hour.
As the question is asking in seconds. Now convert for each second how many meters A is running.
Here we have 3600 seconds for one hour.
So 5000meters or 5*1000meters/3600 which comes to 5*5/18=25/18.
In how many seconds A ran the100meters =100m*25/18sec=72sec.
A has run 8seconds faster than B. Which means B took 8seconds more to complete the run. Therefore 72+8=80Sec.
Now the question is B's speed in km per hour.
Calculate for each sec how many meters he ran=92meters/80sec.
Hence=92/80*18/5 (lets say 3600sec/1000meters) =4.14kmph.
5km per hour=5000 meters per hour.
As the question is asking in seconds. Now convert for each second how many meters A is running.
Here we have 3600 seconds for one hour.
So 5000meters or 5*1000meters/3600 which comes to 5*5/18=25/18.
In how many seconds A ran the100meters =100m*25/18sec=72sec.
A has run 8seconds faster than B. Which means B took 8seconds more to complete the run. Therefore 72+8=80Sec.
Now the question is B's speed in km per hour.
Calculate for each sec how many meters he ran=92meters/80sec.
Hence=92/80*18/5 (lets say 3600sec/1000meters) =4.14kmph.
(1)
Rocktim said:
5 years ago
How come 5/18? Please tell me.
(1)
Sileshi said:
5 years ago
How come 5/18? Please tell me.
Sairam said:
6 years ago
Actually, B has to complete 92 meters in 72 seconds but he is taking an extra 8 seconds time to complete 100 meters which can be concluded from the question. Am I right?
(3)
Mariyappa said:
8 years ago
How get 18 came here?
(1)
Ashutosh kumar said:
8 years ago
A --> 100m.
B --> 92m.
Above is the situation B covers 92m in 72 + 8 = 80s therefore we have taken 92m to calculate the speed of B.
B --> 92m.
Above is the situation B covers 92m in 72 + 8 = 80s therefore we have taken 92m to calculate the speed of B.
Sravs said:
8 years ago
18/5 is the conversion of m/s to km/hr. Because option is in km/hr. We need to convert.
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