Direction : The table given below shows the data about track record of car…
2021
Direction : The table given below shows the data about track record of car racing game, where 4 cars P, Q, R and S are competing to reach finishing line which is at a distance of 3000 m from their initial starting point.
1. Drift refers to over starting intentionally done by driver.
2. While calculating average speed, do not consider time taken in drift/crash.
3. Points = 50 × drifts – 20 × crashed
Speed of car S is what percentage more than that of car Q?
- A.
25%
- B.
33 ⅓%
- C.
50%
- D.
20%
- E.
15%
Attempted by 3 students.
Show answer & explanation
Correct answer: D
Concept
Speed = Distance ÷ Time. When two objects cover the same distance, the one that takes less time has the greater speed. To find how much percentage one speed exceeds another, use ((Higher speed − Base speed) ÷ Base speed) × 100, where the base is the value being compared against — here, car Q.
Application
Both cars cover the same distance of 3000 m, so compute each speed from its time.
Speed of car Q = 3000 ÷ 120 = 25 m/s.
Speed of car S = 3000 ÷ 100 = 30 m/s.
Required percentage = ((30 − 25) ÷ 25) × 100 = (5 ÷ 25) × 100 = 20%.
Cross-check
Since both travel the same distance, speed is inversely proportional to time, so the percentage can be found from the times alone: ((120 − 100) ÷ 100) × 100 = 20%. Both methods agree, so car S is 20% faster than car Q.