## Saturday, 8 August 2015

1. A person riding a bike crosses a bridge with a speed of 54 km/h. what is the length of the bridge, if
he takes 4 min to cross the bridge?
1) 3600 m  2) 2800 m  3) 3500 m  4) 4500 m  5) None of these
Solution: (1)
Length of the bridge = Distance travelled by the person in 4 min
= Speed x Time
Speed = 54 km/h = 54 x 5/8 = 3 x 5 = 15 m/s
Time = 4 min = 4 x 60 = 240 s
Therefore required length = 15 x 240 = 3600m

2. Two men start together to walk a certain distance, one at 4 km/h and another at 3 km/h. the
former arrives half an hour before the latter. Find the distance.
1) 6 km  2) 9 km  3) 8 km  4) 7 km  5) None of these
Solution: (1).let total distance = x km
According to the question,
x/3 - x/4 = ½ ; x/12 = ½ = x = 6 km

3. Moving 6/7 of its usual speed a train is 10 min late. Find its usual time to cover the journey.
1) 25 min  2) 15 min  3) 35 min  4) 60 min  5) None of these
Solution: (4).
New speed = 6/7 of usual speed
Now, time taken = 7/6 of usual time
(7/6 of the usual time) – (usual time) = 10 min
= 1/6 of the usual time = 10 min
Therefore usual time = 60 min

4. A student walks from his house at 2 ½ km/h and reaches his school late by 6 min. Next day, he
increases his speed by 1 km/h and reaches 6 min before school time.  How far is the school from his
house?
1) 5/4 km  2) 7/4 km  3) 9/4 km  4) 11/4 km  5) None of these
Solution: (2).
Let the required distance = x
According to the question ,
x/ 5/2 - x / 7/2 = 12/60
(difference between two times = 6 + 6= 12min)
= 2x/5 - 2x/7 = 1/5
14x - 10x = 7
4x = 7
X = 7/4 km

5. A person can walk a certain distance and drive back in 6 h. He can also walk both ways in 10 h. how
much time will he take to drive both ways?
1) 2 h  2) 2 ½ h  3) 5 ½  4) 4 h  5) None of these
Solution: (1).
Since, he takes 10 h to walk both ways, the number of hours to walk one way for him will be 5. If he
walks one way and drives back the same way it takes him 6 h which means that the number of h taken o
drive one way is 6 – 5 = 1 h. Thus, number of hours to drive both ways will be 2.