Question Detail

The ratio between the speeds of two trains is 7: 8. If the second train runs 400 kms in 4 hours, then the speed of the first train is ?

83.5 km/hr
84.5 km/hr
86.5 km/hr
87.5 km/hr

Answer: Option D

Explanation:

Let the speeds of two trains be 7X and 8X km/hr.

\begin{aligned}
8X = \frac{400}{4} \\
=> X = 12.5 Km/hr

\end{aligned}
So speed of first train is 12.5*7 = 87.5 km/hr

1. A person travels equal distances with speed of 3 km/hr, 4 km/hr and 5 km/hr and takes a total of 47 minutes. Find the total distane

3 km
4 km
6 km
9 km

Answer: Option A

Explanation:

Let the distance be 3x km,
then,
\begin{aligned}
\frac{x}{3} +\frac{x}{4} +\frac{x}{5} = \frac{47}{60} \\
\frac{47x}{60} =\frac{47}{60} \\
x = 1
\end{aligned}
So total distance = 3*1 = 3 Km

2. Two boys starting from the same place walk at a rate of 5kmph and 5.5kmph respectively. What time will they take to be 8.5km apart, if they walk in the same direction?

15 hours
16 hours
17 hours
18 hours

Answer: Option C

Explanation:

In this type of questions we need to get the relative speed between them,
The relative speed of the boys = 5.5kmph – 5kmph
= 0.5 kmph

Distance between them is 8.5 km
Time = Distance/Speed
Time= 8.5km / 0.5 kmph = 17 hrs

3. A car moves at 80 km/hr. What is the speed of the car in meters per second ?

\begin{aligned} 20\frac{2}{9} m\sec \end{aligned}
\begin{aligned} 22\frac{2}{9} m\sec \end{aligned}
\begin{aligned} 24\frac{2}{9} m\sec \end{aligned}
\begin{aligned} 26\frac{2}{9} m\sec \end{aligned}

Answer: Option B

Explanation:

\begin{aligned}
Speed = \left(80*\frac{5}{18}\right) m/sec \\
= \frac{200}{9} m/sec \\
= 22\frac{2}{9} m\sec
\end{aligned}

4. A train traveled at an average speed of 100 km/hr, stopping for 3 minutes after every 75 km. How long did it take to reach its destination 600 km from the starting point.

6 hours 24 mins
6 hours 21 mins
6 hours 18 mins
6 hours 15 mins

Answer: Option B

Explanation:

Time taken to cover 600 km = 6 hours [because train speed is 100 km/hr]

Number of stops =
begin{aligned}
frac{600}{75} - 1 = 7 \
text{Total time on stops =}7*3 = 21 mins

end{aligned}
Total time taken by train = 6 hours 21 mins

5. A man in a train notices that he can count 41 telephone posts in one minute. If they are known to be 50 metres apart, then at what speed is the train travelling?

60 km/hr
100 km/hr
110 km/hr
120 km/hr

Answer: Option D

Explanation:

Number of gaps between 41 poles = 40
So total distance between 41 poles = 40*50
= 2000 meter = 2 km
In 1 minute train is moving 2 km/minute.
Speed in hour = 2*60 = 120 km/hour