DXC Quants Problems on Trains Quiz 4

Answer: B
Explanation:

Distance d = 1050 km
let S be the speed
Justin Bieber travels 15 hours a day (i.e 24 - 9)
so in total, he walks = 7 x 15 = 105 hrs.
S = 1050/105 => 10 km/h

given 3/2 of the previous speed
so 3/2 * 10 = 15
New speed = 15 km/h
Now he stops 10 hrs a day which means it covers 14 hrs a day.
time = 720/15 => 48 hrs ~ 2 days
So he will take 2 days to cover 720 km.

Answer: C
Explanation:

The number of gaps between 61 shops = 60
So the total distance between 61 shops = 60*30
= 1800 meters = 1.8 km
In 1 minute train is moving 1.8 km/minute.
Speed in hour = 1.8 * 60 = 108 km/hour

Answer: A
Explanation:
The relative speed of the boys = 16 kmph – 14 kmph
= 2 kmph

Distance between them is 10 km
Time = Distance/Speed
Time= 10km / 2 kmph = 5 hrs

Answer: B
Explanation:

In 1hr, the bus covers 60 km without stoppages and 40 km with stoppages.

Stoppage time = time takes to travel (100 - 60) km
i.e 40 km at 100 km/hr.
stoppage time = 40/60 hrs = 40 min.

Answer: B
Explanation:
Speed when he travels from Delhi to Patna = 80
Speed on return trip = 175% of 80 = 140 km/hr.
Average speed = (2 x 80 x 140)/(80 + 140) = 101.82 km/hr. ~ 102 km/hr

Answer: B
Explanation:
Initial speed = 120km/hr
Total distance = 120 x 8 = 960 km
New speed = 960/2 =480km/hr
Increase in speed = 480 - 120 = 360 km/hr

Answer: D
Explanation:

Let the time taken by train be 't' hrs.
Then,
50t = 25(t + 10/60)
40t = 35t + 25/6
5t = 5/6 hrs
Therefore, the Required length of the total journey d = s x t
= 40 x 5/6
= 100/3 km

Answer: D
Explanation:
As we know Speed = Distance / Time
for average speed = Total Distance / Total Time Taken
Thus, Total Distance = 328 + 512 = 840 km
Thus, Total Speed = 8
Average Speed = 840/8 => 105 kmph.

Answer: D
Explanation:
The first Autorikshaw covers 160 km in 5 hrs
=> Speed = 160/5 = 32 kmph
Now the second Autorikshaw covers the same distance in 1 hour less than the first = 4 hrs
=> Speed of the second train = 160/4 = 40 kmph
Now, the required difference in distance in 1 hour = 40 - 32 = 8 km.

Answer: A
Explanation:
Given that,
1st train speed = 80 km/hr
2nd train speed = 44 km/hr
Hence,
the relative speed of the two trains is 80 - 44 = 36 km/hr = 36 x 5/18 = 10 m/s
Therefore, the first train crosses the second train i.e (105 +205)m of distance with a speed of 10m/s.
Hence, (105 +205)/10 = 31 secs