Solution:

This is a tricky question. The velocity data may confuse many but if you look at the question closely, it is totally irrelevant.

You are being told that Wally sees a train after every five minutes. The velocity will not matter therefore and you need not look in that direction. All you want to know is that he sees a train after every 5 minutes and he completes the journey in an hour or 60 minutes.

All you need to do is divide 60 by 5 and you will get the answer which is 12.

Solution:

To solve this question, we will have to use the concept of relative speed.

Let us assume that the distance between the station A and B is D Miles
The relative speed at which the train are approaching each other is 20 + 15 = 35 mph
When the train collides with each other, the sum of the distance covered will be the distance between the stations i.e. D.
Now Speed = Distance/Time
Which means that the trains will collide in d/35 hours after their start

Another constant things we have here is the speed of the vulture i.e. 25 mph.
Thus by the time the trains collide, the vulture would have covered
25*(D/35) miles = 5D/7 Miles

Solution:

Let x be the distance of train from bridge, 2l be the length of the bridge and s be the speed of cow

Then according to the question
(x-2)/4s = ( l-5)/s
4l-a = 18 ----- (1)
Also
(a+2l-2)/4s = (l+5-2)/s
a-2l = 14 ----- (2)

On adding (1) and (2), we get
2l = 32

Thus the length of the bridge is 32 meters.

Solution:

Distance = d
Speed = s
Time = t
Now, d = s*t

When t1 = (3/4)t
Then,
d = s1*t1

Applying t1 value,
s*t = s1*(3/4)t
Then
s1/s = 4/3

Therefore, increase in speed = (s1/s - 1)
=4/3 - 1
=1/3
=33.33%

Solution:

One thing which you must keep in mind is that we must convert everything to one unit.
The speed of dog = 13 km/h i.e. 8.125 miles/h

Time I will take to catch the thief = 13/1/5 hours = 8.67 hours

Total distance that my dog will travel = 8.125 * 8.67 = 70.44 miles.

Solution:

The passenger will occupy three seats, per head payable amount will be 26.89.

80.67 rupees cannot be divided by 3.

Thus the number of occupied seats will be 3.
And unoccupied seats = 40-3 = 37.

Solution:

7 AM

Explanation:
Train A covers 20x3 km i.e. 60 kms in 3hrs and
Train B covers 25x2 km i.e. 50 kms in 2hrs => total of 110kms