Two trains start from same place at same time at right angles to each other. Their speeds are 36km/hr and 48km/hr respectively. After 30 seconds the distance between them will be ?

Correct Answer: 32 sec

Explanation:

Given that,

1st train speed = 62 km/hr 

2nd train speed  = 44 km/hr

Hence the relative speed of two trains is : 62-44 = 18 km/hr = 18 × 5 18 m/s = 5 m/s.

There fore, the first train crosses the second train i.e (85+75)mts of distance with a speed of 5m/s in, 

 

time =  d i s tan c e s p e e d = 85 + 75 5 = 32 sec.

Correct Answer: 60 kmph

Explanation:

Speed of lorry = 360 12 = 30 kmph

Speed of van = 250 100 x 30 = 75 kmph

Speed of bike = 3 5 x 75 = 45 kmph

Therefore, now required average speed of bike and van  = 75 + 45 2= 60 kmph.

Correct Answer: 8 hrs

Explanation:

Given speed of the bike after servicing = 55 kmph

Time taken for travelling some distance at 55 kmph = 5 hrs

Then, 

Distance = Speed x Time = 55 x 5 = 275 kms.

Now, 

Speed of the bike before servicing = 35 kmph

Distance = 275 kms

Now, Time = Distance/Speed = 275/35 = 7.85 hrs =~ 8 hrs.

Correct Answer: Option B

Explanation:

Man walked 6 km at 1.5 kmph, again he walked 8 km at speed of 2 kmph and 40 km at a speed of 8kmph
time taken indivisually:
=> 6/1.5 = 4 m
=> 8/2 = 4 m
=> 40/8 = 5 m

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Average speed of man= total distance/ total time
=> 54/13 =  4 2 13 kmph

Correct Answer: 204 m

Explanation:

To find the minimum distance, we have to get the LCM of 75, 80, 85

Now, LCM of 75, 80, 85 = 5 x 15 x 16 x 17 = 20400

Hence, the minimum distance each should walk so that thay can cover the distance in complete steps = 20400 cms = 20400/100 = 204 mts.

Correct Answer: 4 km/hr

Explanation:

Let P's speed = x km/hr. Then, Q's speed = (7 - x) km/ hr.

 

So, 24/x + 24/(7 - x) = 14

 

x 2 - 98x + 168 = 0

 

(x - 3)(x - 4) = 0 => x = 3 or 4.

 

Since, P is faster than Q,

 

so P's speed = 4 km/hr and Q's speed = 3 km/hr.

Correct Answer: 41.25 days

Explanation:

Given Karthik can cover the distance of 200 kms resting 2 hrs per day in 22 days.

 

Let the initial speed be '1'

 

Hence, Time = 22(24hrs - 2)

 

Noe new speed = 2/3

 

Let the number of days he take be 'D'

 

Therefore,  22 24 - 2 x 3 200 = D 24 - 2 x 2 250

 

D = 11 x 3 x 5/4 = 41.25 days. = 41 1/4 days.

Correct Answer: 24 kmph

Explanation:

Let the speed of the train be 'S' kmph

From the given data,

Distance = Length of train = D = 200 mts = 200 x 18/5 kms

Time = 10 sec

given speed of the motorcycler = 12 kmph

Relative speed as they are moving in the same direction = (S - 12) kmph

$$\begin{gathered} ( S - 12) = 200 x 18 5 15 \\ S - 12 = 48 \\ S = 60 kmph \\ \end{gathered}$$

Hence, the speed of the train = S = 60 kmph

Now,

Let the speed of the jeep be 'x' kmph

$$\begin{gathered} 60 - x = 200 x 18 5 20 \\ 60 - x = 36 \\ x = 60 - 36 \\ x = 24 kmph \end{gathered}$$

 

Therefore, the speed of the jeep = x = 24 kmph.

Correct Answer: 7.36 kms

Explanation:

Total running distance in four weeks = (24 x 240) + (4 x 400)

= 5760 + 1600

= 7360 meters

= 7360/1000

=> 7.36 kms

Correct Answer: 9 kms

Explanation:

The first train covers 180 kms in 5 hrs

=> Speed = 180/5 = 36 kmph

Now the second train covers the same distance in 1 hour less than the first train => 4 hrs

=> Speed of the second train = 180/4 = 45 kmph

Now, required difference in distance in 1 hour = 45 - 36 = 9 kms.