SI practice questions: Guide on questions related to time and distance

This article is in continuation to the last article on preparation for the Sub-Inspector of Police recruitment exam. Here are some practice questions and answers along with explanations on the Time and Distance topic. 1. Formulas The sound system in cinema theatre is ‘DTS’. It is very is to remember. D = T X S […]

This article is in continuation to the last article on preparation for the Sub-Inspector of Police recruitment exam.

Here are some practice questions and answers along with explanations on the Time and Distance topic.

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1. Formulas

The sound system in cinema theatre is ‘DTS’. It is very is to remember.

D = T X S
T =
S =

2. Units

If Distance in KM and Time in Hours then Speed should be in KM/Hr

If Distance in meter and Time in sec then Speed should be in m/sec

3. Units conversion

1km = 1000 m

1hr = 3600 sec

To convert speed from km/hr to m/sec, multiply by

To convert speed from m/sec to km/hr, multiply by

4. If a person travelled two equal distances at ‘x’ km/hr and ‘y’ km/hr, then his average speed =

5. If a person travelled three equal distances at ‘x’ km/hr, ‘y’ km/hr and ‘z’ km/hr, then his average speed =

6. If a person travelled two or more than two equal or unequal distances with different speeds, then his average speed = Total distance/ Total time

7. If two persons A and B start at the same time from two points P and Q towards each other and after crossing they take T1 and T2 hours in reaching Q and P respectively, then

A’s Speed : B’s Speed = T2 : T1

8. If the time taken is constant, the distance travelled is proportional to the speed, that is, more the speed more the distance travelled in the same time.

9. If the speed is constant, the distance travelled is proportional to the time taken, that is, more the distance travelled, more the time taken at the same speed.

10. If the distance travelled is constant, the speed is inversely proportional to the time taken, that is , more the speed, less the time taken for the same distance travelled.

Examples

1. A car covers a distance of 816 km in 12 hours. What is the speed of the car?
1) 60km/hr 2) 62 km/hr 3) 64 km/hr 4) can’t be determined 5) None of these
Ans: (5)
Speed = = 68 km/ hr

2. A car travels a distance of 75 km at the speed of 25 km/hr. It covers the next 25 km of its journey at the speed of 5 km/hr and the last 50 km of its journey at the speed of 25 km/hr. What is the average speed of the car?
1) 40 km/hr 2) 25 km/hr 3) 15 km/hr 4) 12.5 km/hr 5) None of these
Ans: (3)

Time taken to cover first 75 km of distance = = 3 hrs
Time taken to cover next 25 km of distance = = 5 hrs
Time taken to cover last 50 km of its journey = = 2 hrs
Average Speed = Total distance / Total Time = = = 15km/hr

3. The speed of truck is rd of the speed of a train. The train covers 1230 km in 5 hours. What is the speed of the truck?
1) 85 km/hr 2) 82 km/hr 3) 81 km/hr 4) 87 km/hr 5) None of these
Ans: (2)

The speed of thee train = = 246 km/hr
The speed of the truck = X 246 = 82 km/hr

By Banda Ravipal Reddy
Director, SIGMA
Sai Institute of General Mental Ability
Hyderabad

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