Practice Questions
Concept Explanation
Speed–distance DS items test whether distance, speed, or time can be found from given relations.
Standard Answer Choices
- A — Statement I alone is sufficient; Statement II alone is not.
- B — Statement II alone is sufficient; Statement I alone is not.
- C — Both together are sufficient, neither alone.
- D — Either statement alone is sufficient.
- E — Neither alone nor together is sufficient.
Speed/Distance DS Focus
Use Distance = Speed × Time. Convert km/hr and m/s when needed: m/s = (5/18) × km/hr.
Common Traps in Speed/Distance Problems
- Adding speeds instead of using harmonic mean for equal distances.
- Confusing average speed with average of two speeds.
- Mixing upstream/downstream without current speed.
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Q1 Easy
A car at 60 km/hr for 3 hours covers:
ExplanationDistance = 60 × 3 = 180 km. -
Q2 Easy
180 km at 45 km/hr takes:
ExplanationTime = 180/45 = 4 hr. -
Q3 Medium
Train 120 m long at 54 km/hr crosses a pole in:
ExplanationSpeed = 15 m/s; time = 120/15 = 8 sec. -
Q4 Easy
For “What is distance?” — I: speed = 50 km/hr; II: time = 4 hr. DS answer?
ExplanationDistance = speed × time. Need both. -
Q5 Hard
Average speed for 60 km at 40 km/hr and 60 km at 60 km/hr is:
ExplanationTotal 120 km in 1.5 + 1 = 2.5 hr; avg = 48 km/hr. -
Q6 Medium
Relative speed of two trains 72 km/hr and 54 km/hr in same direction is:
ExplanationDifference = 18 km/hr. -
Q7 Easy
Boat 15 km/hr in still water, stream 3 km/hr. Downstream speed is:
Explanation15 + 3 = 18 km/hr.
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Q8 Hard
A walks 5 km at 4 km/hr and 5 km at 6 km/hr. Average speed is:
Explanation10 km in 1.25 + 0.833 = 2.083 hr; avg ≈ 4.8 km/hr. -
Q9 Medium
For “Meeting time?” — I: distance = 300 km; II: combined speed = 100 km/hr. DS answer?
ExplanationTime = 300/100 = 3 hr. Need both. -
Q10 Medium
72 km/hr equals:
Explanation72 × 5/18 = 20 m/s. -
Q11 Medium
Two cities 240 km apart; speeds 60 and 40 km/hr toward each other. Meet in:
ExplanationRelative speed = 100; time = 240/100 = 2.4 hr. -
Q12 Hard
For “Speed of train?” — I: crosses 800 m platform in 60 sec; II: train length 200 m. DS answer?
ExplanationSpeed = (200+800)/60 = 16.67 m/s. Need both length and crossing time/distance. -
Q13 Hard
A cyclist goes 30 km upstream and back in 5 hr; stream 3 km/hr. Speed in still water is:
Explanation30/(v−3) + 30/(v+3) = 5 ⇒ v = 15 km/hr. -
Q14 Medium
For “Is average speed above 50 km/hr?” — I: total distance 200 km; II: total time 3.5 hr. DS answer?
ExplanationAverage = 200/3.5 ≈ 57.1 km/hr. Need both.
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DS1 Easy
What is the distance traveled?
Statement ISpeed is 60 km/hr.
Statement IITravel time is 3 hours.
ExplanationDistance = 60 × 3 = 180 km. Need both speed and time. -
DS2 Hard
What is the average speed for a round trip of equal distances at 40 km/hr and 60 km/hr?
Statement IEach leg is 120 km.
Statement IITotal travel time is 5 hours.
ExplanationStatement I: total 240 km in 3 + 2 = 5 hr ⇒ 48 km/hr. Statement II: 240/5 = 48 km/hr.
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DS3 Medium
When do two trains meet?
Statement IThey start 300 km apart.
Statement IITheir combined speed is 100 km/hr.
ExplanationMeeting time = 300/100 = 3 hr. Need both. -
DS4 Medium
What is the speed of the train in m/s?
Statement IA 200 m train crosses an 800 m platform in 60 seconds.
Statement IIThe train crosses a pole in 12 seconds.
ExplanationStatement I: 1000/60 = 16.67 m/s. Statement II: 200/12 = 16.67 m/s.