1. A person crosses a 600 m long street in 5 minutes. What is his speed in km per hour?

**Answer: **7.2

**Explanation:**
Speed = 600/(5*60) m/sec. = 600/300 m/sec = 2 m/sec

Now convert m/sec to km/hr

= 2 x 18/5 km/hr = 7.2 km/hr.

2. How Many minutes does shyam take to cover a distance of 500 m, if he runs at a speed of 20km/h?

**Answer: **1 min 30 sec.

**Explanation:**
Ram's speed = 20 km/h = (20 * 5/18) m/sec. =50/9 m/sec.

**Formula Used: Time = Distance/Speed. **

Time taken to cover 500m = 500/(50/9) sec

= (500 *9)/50 sec = 90 sec = 1 min 30 sec..

3. An Athlete runs 200 metres race in 24 seconds. His speed is:

**Answer: **30 km/hr

**Explanation:**
Speed = (200/24) m/sec = 25/3 m/sec

convert m/sec to km/hr

(25/3 * 18/5) km/hr = 30 km/hr.

4. Albert is travelling on his cycle and has calculated to reach point A at 2 P.M. if he travels at 10 kmph, he will reach there at 12 noon if he travels at 15 kmph. At what speed must he travel to reach A at 1 P.M.?

**Answer: **12 kmph

**Explanation:**
Let's Assume the distance travelled Albert = x km.

Formula Used: Time = Distance/Speed

so (x/10 - x/15) = 2 hrs

=> (3x - 2x)/30 = 2 hrs.

=> (3x - 2x) = 60

x = 60 km.

Time taken to travel 60 km at 10 km/hr = 60/10 hrs = 6 hrs.

Formula Used: Speed = Distance/Time

So, Albert started 6 hours before 2 P.M. i.e @ 8 A.M.

Required speed = 60/5 kmph. = 12 kmph.

5. Raghav had to walk a certain distance. He walked half the distance at a speed of 4 km/hour and the remaining half at a speed of 5 km/hour. If the total time taken was 9 hour, the distance was

**Answer: **40 km

**Explanation:**
Let half of the distance travelled be d.

Time taken at the speed of 4 km/hr = (d/4)

Time taken at the speed of 5 km/hr = (d/5)

Therefore, total time = (d/4) + (d/5) = 9 hrs.

? (5d + 4d)/20 = 9

? 9d = 180

? d = 20.

Therefore total distance = d x 2 = 40 kms

6. Virat travelled 75 kms in 7 hours. He went some distance at the rate of 12 km/hr and the rest at 10 km/hr. How far did he travel at the rate of 12 km/hr?

**Answer: **30 kms

**Explanation:**
Let the distance travelled at the rate of 12 kmph be x km

Time taken to travel this distance = x/12 .......(1)

Then the distance travelled at the rate of 10 km/hr will be (75 - x)

Time taken to travel this distance = (75 - x)/10 .......(2)

Total time taken to cover the total distance = 7 hrs

=>(x/12) + (75 - x)/10 = 7 [sum of (1) and (2)]

=> (10x + 900 - 12x) = 840

=> -2x = -60

=> x = 30.

Therefore, the distance travelled at the rate of 12 km/hr = 30km.

7. A boy rides his bicycle 10 kms at an average speed of 12 kmph and again travels 12 kms at an average speed of 10 kmph. His average speed for the entire trip is approximately:

**Answer: **10.8 kmph

**Explanation:**
Average speed is represented by total distance divided by the time taken.

Total distance = 10 kms + 12 kms = 22 kms

Total Time = (10/12) + (12/10)

? (10/12) + (12/10) = (100 + 144)/120 = 244/120 hrs

Average speed = 22/(244/120) = 10.8 kmph.

Average speed for the entire trip is 10.8 kmph.

8. An athlete runs half of the distance at the speed of 10 km/hr and remaining 15 km at the speed of 20 km/hr, how much time will be taken to cover the total distance?

**Answer: **135 mins

**Explanation:**
We know that time = distance/speed

Time taken by the athlete for the first half = 15/10

And time taken by the athlete for the second half = 15/20

Total time = 15/10 + 15/20 = (45/20) x 60 = 135 mins

Time taken to cover the total distance is 135 mins.

9. A person travelled by train for 1 hour at a speed of 50 kmph. He then travelled by a taxi for 30 minutes at a speed of 32 kmph to complete his journey. What is the average speed at which he travelled during the journey?

**Answer: **44 kmph

**Explanation:**
Total distance travelled in 1 hour

= 50 + (&frac; x 32) km

= 66 km

? Average speed = Total distance/Total time

= 66/(3/2) = 44 kmph.

10. A car covers four successive 6 km stretches at speeds of 25 kmph, 50 kmph, 75 kmph and 150 kmph respectively. Its average speed over this distance is

**Answer: **50 kmph

**Explanation:**
Time = Distance/Speed

Time taken for each 6 km can be given by

6/25, 6/50, 6/75 and 6/150

Total time = (6/25) + (6/50) + (6/75) + (6/150) = (36 + 18 + 12 + 6)/150 = 72/150

Average speed = Distance/time = (24/72) x 150 = 50 kmph