Which of the following statement(s) is/are wrong? A. A man runs at a speed of…
2025
Which of the following statement(s) is/are wrong?
A. A man runs at a speed of 20 km/hr and covers a distance of 400 m. The time taken by the man to cover 400 m is 8 minutes.
B. A person covers a certain distance at x km/hr and an equal distance at y km/hr. The average speed during the whole journey is frac 2xy/x+y km/hr.
C. A Cyclist covers a distance of 750 m in 2 (1/2) minutes. The speed of the cyclist is 18 km/hr.
D. A speed of x km/hr is equal to 5x/18 m/sec
Choose the most appropriate answer from the options given below:
- A.
A Only
- B.
A and B Only
- C.
A and C Only
- D.
B, C and D Only
Attempted by 8 students.
Show answer & explanation
Correct answer: A
To determine the wrong statement, we analyze each option using speed-distance-time relationships.
Statement A: Speed = 20 km/hr, Distance = 400 m = 0.4 km. Time = Distance / Speed = 0.4 / 20 = 0.02 hours. Converting to minutes: 0.02 * 60 = 1.2 minutes.
The statement claims 8 minutes, which is incorrect.
Statement B: For equal distances at speeds x and y, average speed = 2xy / (x+y).
This is the correct harmonic mean formula.
Statement C: Distance = 750 m, Time = 2.5 min = 150 sec. Speed = 750 / 150 = 5 m/s. Converting to km/hr: 5 * (18/5) = 18 km/hr. This is correct.
Statement D: To convert km/hr to m/sec, multiply by 5/18. So x km/hr = (5x)/18 m/sec. This is correct.
Since only Statement A is wrong, Option A (A Only) is the correct choice.