Speed, Time and Distance
 A and B are 20 km apart. A can walk at an average speed of 4 km/hr and B at 6 km/h. If they start walking towards each other at 7:000 am, when they will meet?

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Sum of distance traveled by them after T hours
6T + 4T = 20 KM
T = 2 hours.Correct Option: C
Suppose they will meet after T hours.
Distance = Speed x Time
Sum of distance traveled by them after T hours
6T + 4T = 20 km
T = 2 hours.
So they will meet at 7:00 AM + 2 hours = 9:00 AM
 Arjun runs a distance of 1500 m in 5 minutes. What is his speed in Km/hr ?

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Speed in Km/hr = Speed in m/sec x 18/5
Correct Option: B
Speed = (1500/300 ) m/sec
= 5 m/sec
= (5 x 18/5 ) km/hr
= 18 km/hr
 In how many minutes will Rohit cover a distance of 800 m, if he runs at speed of 10 km/hr?

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Speed in m/sec = Speed in km/hr x 5/18
Correct Option: D
Rohit's speed = 10 Km/hr = (10 x 5/18) m/sec = 50/18 m/sec
Time taken to cover 800 m = (800 / (50/18) ) sec
= (800 x 18/50) sec = 288 sec = 4 min 48 sec
 A plane flies along the four sides of a square field at a speed of 200, 400, 600 and 800 km/hr. Then find the average speed of plane around the square field.

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Let the side of the square field be x and the speed of plane be y
x/200 + x/400 + x/600 + x/800 = 4x/yCorrect Option: D
Let the side of the square field be x and the average speed of plane be y
x/200 + x/400 + x/600 + x/800 = 4x/y
⇒ 25x/2400 = 4x/y
⇒ y =384
∴ Average speed is 384 km/hr
 Laxman has to cover a distance of 6 km in 45 minutes . If he cover one half of the distance in 2/3^{rd } time . what should be his speed to cover the remaining distance in the remaining time?

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∵ Time left = (1/3 X 45/60) hr.
= 1/4 hr.
Distance left = 3km
∴ speed required = [3 / (1/4) ] km/hr.Correct Option: C
∵ Time left = (1/3 X 45/60) hr.
= 1/4 hr.
Distance left = 3km
∴ speed required = [3 / (1/4) ] km/hr.
= 3 x 4
=12km/hr .