Question Detail

A walks around a circular field at the rate of one round per hour while B runs around it at the rate of six rounds per hour. They start at same point at 7:30 am. They shall first cross each other at ?

7:15 am
7:30 am
7: 42 am
7:50 am

Answer: Option C

Explanation:

Relative speed between two = 6-1 = 5 round per hour

They will cross when one round will complete with relative speed,
which is 1/5 hour = 12 mins.

So 7:30 + 12 mins = 7:42

1. 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}

2. A cyclist covers a distance of 750 meter in 2 minutes 30 seconds. What is the speed in km/hr of cyclist

16 km/hr
17 km/hr
18 km/hr
19 km/hr

Answer: Option C

Explanation:

\begin{aligned}
Speed = \frac{Distance}{Time} \\
Distance = 750 meter \\
Time = \text{2 min 30 sec} = 150 sec \\
Speed = \frac{750}{150} = 5 m/sec \\

=> 5*\frac{18}{5} km/hr = 18 km/hr
\end{aligned}

3. A thief is noticed by a policeman from a distance of 200 m. The thief starts running and the policeman chases him. The thief and the policeman run at the rate of 10 km and 11 km per hour respectively. What is the distance between them after 6 minutes ?

50 meter
100 meter
110 meter
None of above

Answer: Option B

Explanation:

Relative speed of the thief and policeman = (11 – 10) km/hr = 1 km/hr

Distance covered in 6 minutes =
\begin{aligned}
\frac{1}{60}*6 = \frac{1}{10} \\
= 100 meters
\end{aligned}

So distance between them after 6 minutes = 200 - 100
= 100 meters

4. An athlete runs 200 meters in 24 seconds. His speed is ?

10 km/hr
17 k/hr
27 km/hr
30 km/hr

Answer: Option D

Explanation:

\begin{aligned}
Speed = \frac{Distance}{Time} \\
= \frac{200}{24}m/sec = \frac{25}{3} m/sec \\
\frac{25}{3}*\frac{18}{5} km/hr = 30 km/hr
\end{aligned}

5. How many minutes does Aditya take to cover a distance of 400 m, if he runs at a speed of 20 km/hr

\begin{aligned} 1\frac{1}{5} min\end{aligned}
\begin{aligned} 2\frac{1}{5} min\end{aligned}
\begin{aligned} 3\frac{1}{5} min\end{aligned}
\begin{aligned} 4\frac{1}{5} min\end{aligned}

Answer: Option A

Explanation:

We know that,
\begin{aligned}
Time = \frac{Distance}{Speed} \\
Speed = 20\text{ km/hr} = 20*\frac{5}{18}{ m/sec} \\
= \frac{50}{9}{ m/sec} \\

\text{ Time =} \left(400*\frac{9}{50}\right) \\
= 72 {sec} = 1\frac{1}{5}{ min}
\end{aligned}