In a 500 m race, A beats B by 40 metres or 8 seconds. Find A's time over the course.
A)
100 s
B)
92 s
C)
108 s
D)
98 s
Correct Option - B
Explanation
B covers 40 meters in 8 seconds.
B's speed = 40/8 = 5 m/s
Time taken by B to cover 500m
= 500/5
= 100 seconds
A beats B by 8 seconds. Hence,
Time taken by A
= 100-8
= 92 seconds
A and B take part in a 100 m race. A gives B a start of 10 m and still beats B by 5 seconds. If A's speed is 2.5 m/s, find B's speed.
A)
2 m/s
B)
2.5 m/s
C)
1.5 m/s
D)
2.25 m/s
Correct Option - A
Explanation
Time taken by A to cover 100 m
= 100/2.5
= 40 seconds
A gives B a start of 10 m. Hence, B covers only 90 m.
A beats B by 5 seconds.
Hence, time taken by B to cover 90 m
= 40+5
= 45 seconds
B covers 90 m in 45 seconds.
B's speed
= 90/45
= 2 m/s
A's speed is twice B's speed. In a 100m race, how many metres start can A give B so that the race ends in a dead heat?
A)
50 m
B)
25 m
C)
10 m
D)
75 m
Correct Option - A
Explanation
For the race to end in a dead heat,
both A and B should reach the winning post at the same time.
A's speed is twice B's speed.
To run the same distance,
time taken by B=2*(time taken by A)
Time taken by B to run 100 m
= 2*Time taken by A to run 100 m
Time taken by B to run 50 m
= Time taken by A to run 100 m
Hence, A can give B a start of 50 m.
The speeds of A and B are in the ratio 3:4. B gives A a start of 30 m. How far should the winning post be so that the race ends in a dead heat?
A)
100 m
B)
200 m
C)
150 m
D)
120 m
Correct Option - D
Explanation
Let A's speed be 3x m/s and
B's speed be 4x m/s
Let the distance of the winning post be l m.
Time taken by A to finish the race
= (l-30)/3x
Time taken by B to finish the race
= l/4x
For the race to end in a dead heat,
(l-30)/3x = l/4x
Solving,
l = 120 m
Ram and Lakshman take part in a 200 m race. Ram beats Lakshman by 15 seconds. If Ram's speed is 2 m/s, find the time taken by Lakshman to finish the race.
A)
115 seconds
B)
100 seconds
C)
85 seconds
D)
105 seconds
Correct Option - A
Explanation
Time taken by Ram to finish
= 200/2
= 100 seconds
Ram beats Lakshman by 15 s.
Time taken by Lakshman to finish
= 115 seconds
P can run a 500 m race in 3 minutes and Q in 3 mins 20 seconds. How many meters start can P give Q so that the race ends in a dead heat?
A)
50 m
B)
40 m
C)
25 m
D)
20 m
Correct Option - A
Explanation
Q takes 20 seconds more than P to run 500 m
Distance covered by Q in 3 mins 20 seconds(200 s)
= 500m
Distance covered by Q in 20 seconds
= (500/200)*20
= 50 m
If Q skips 50m, the race can be finished in 3 minutes(same as P).
Hence, for the race to end in a dead heat,
P should give Q a start of 50 m.
In a race, A beats B by 20 m or 10 seconds. Find B's speed.
A)
4 m/s
B)
5 m/s
C)
2 m/s
D)
2.5 m/s
Correct Option - C
Explanation
20 meters are covered by B in 10 seconds.
B's speed
= 20/10
= 2 m/s