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

Answer: Option A

Explanation:

We know total distance is 200 Km
If both trains crossed each other at a distance of 110 km then one train covered 110 km and other 90 km [110+90=200km]
So ratio of their speed = 110:90 = 11:9

Answer: Option A

Explanation:

Let the time in which he travelled on foot = x hour
Time for travelling on bicycle = (9 - x) hr

Distance = Speed * Time, and Total distance = 61 km
So,
4x + 9(9-x) = 61
=> 5x = 20
=> x = 4

So distance traveled on foot = 4(4) = 16 km

Answer: Option C

Explanation:

Speed while going = 40 km/hr
Speed while returning = 150% of 40 = 60 km/hr

Average speed =
$$\begin{aligned} \frac{2xy}{x+y} \\ = \frac{2*40*60}{40+60} = \frac{4800}{100} \\ = 48 Km/hr \end{aligned}$$

Answer: Option D

Explanation:

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

Answer: Option B

Explanation:

Two things to give attention on this question.
First time is in minutes, we need to change it to seconds to get speed in m/sec, then we need to get the final answer in km/hr.
So lets solve this.

$$\begin{aligned} Speed = \frac{Distance}{Time} \\ Distance = 650 meter \\ Time = \text{5 minutes} = 300 sec \\ Speed = \frac{600}{300} = 2 m/sec \\ => 2*\frac{18}{5} km/hr = 7.2 km/hr \end{aligned}$$