701. A man covers a distance of 20 km in 3.5 hours partly by running and partly by walking. If he walks at 4 kmph and runs at 10 kmph, find the distance he covers by walking.
A. 10 km
B. 8 km
C. 12 km
D. 9 km
Let the distance covered by walking be x km
the distance covered by running be (20-x) km Time for walking + time for running = 3.5 hours (x/4)+[(20-x)/10]=3.5 Solving,
5x+40-2x = 70
702. Rayan crosses a 400m bridge in 3 minutes. What is speed?
A. 133.33 kmph
B. 1.33 kmph
C. 4 kmph
D. 8 kmph
He crosses 0.4 km in 3/60th of an hour. Speed = 0.4/(1/20) = 8 kmph
703. Two bikes start at the same time from two destination 300 km apart and travel towards each other. If they cross each other at a distance of 130 km from one of the destination, what is the ratio of their speeds?
D. None of these
704. How much time does a train 125 meters long running at 60 km/hr. take to pass a pole?
60 km/hr = 60 * 5/18 = 16.67 m/s
Speed = distance/time; v = d/t
16.67 = 125/t
t = 7.5s
705. Walking 6/7th of his usual speed, a man is 12 minutes too late. What is the usual time taken by him to cover that distance?
A. 1 hr 42 min
B. 1 hr
C. 2 hr
D. 1 hr 12 min
New speed = 6/7 of usual speed
Speed and time are inversely proportional.
Hence new time = 7/6 of usual time
Hence, 7/6 of usual time – usual time = 12 minutes
=> 1/6 of usual time = 12 minutes
=> usual time = 12 x 6 = 72 minutes
= 1 hour 12 minutes
706. Excluding stoppages, the speed of a bus is 54 kmph and including stoppages, it is 45 kmph. For how many minutes does the bus stop per hour?
speed of the bus excluding stoppages = 54 kmph
speed of the bus including stoppages = 45 kmph
Loss in speed when including stoppages = 54 – 45 = 9kmph
=> In 1 hour, bus covers 9 km less due to stoppages
Hence, time that the bus stop per hour = time taken to cover 9 km
=distance/speed=9/54 hour=1/6 hour = 60/6 min=10 min
707. There are 21 poles with a constant distance between each pole. A car takes 30 seconds to reach the 16th pole. How long does it take to reach the last pole?
A. 39 seconds
B. 40 seconds
C. 39.38 seconds
D. 39.5 seconds
The first pole is crossed at the zeroth second. The timer starts after the car crosses the first pole. Let the distance between each pole be x m. To reach the 16th pole, the distance travelled by the car is 15x. The speed of the car is 15x/30 = x/2 m/s To reach the 21st pole, it has to travel a distance of 20x. Time taken
= 40 seconds
708. A person walking at 5/6th of his usual speed is 40 minutes late to his office. What is his usual travel time to his office?
A. 3 hours 20 minutes
B. 3 hours 15 minutes
C. 3 hours 30 minutes
D. 3 hours
Let his usual speed be x kmph, the distance to his office be y km and his usual travel time be t hrs. y = xt = (5/6)x * (t+(40/60)) Solving the equation,
t = 3.33 hrs = 3 hrs 20 minutes
709. A Man travelled a distance of 61 km in 9 hours. He travelled partly on foot at 4 km/hr and partly on bicycle at 9 km/hr. What is the distance travelled on foot?
A. 12 km
B. 14 km
C. 16 km
D. 18 km
710. A person crosses a 600 m long street in 5 minutes. What is his speed in km per hour?