# 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:
1 year 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.

(2)

Ramanjaneyulu said:
2 years ago

How 5/8 came? please explain me.

Anusha said:
3 years ago

Nice explanation, thanks @Buddhika.

Manikanta said:
4 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.

Rocktim said:
4 years ago

How come 5/18? Please tell me.

(1)

Sileshi said:
5 years ago

How come 5/18? Please tell me.

Sairam said:
5 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:
7 years ago

How get 18 came here?

Ashutosh kumar said:
7 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:
7 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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