The wheel of a car covers a distance of 44 km in 5000 revolutions. The radius of the wheel is :
14 cm
7 cm
28 cm
25 cm
Answer is Right!
Answer is Wrong!
This question was previously asked in
UPSC CISF-AC-EXE – 2023
Total distance = 44 km = 44,000 meters.
Number of revolutions = 5000.
Circumference C = Total distance / Number of revolutions = 44,000 m / 5000 = 44/5 m = 8.8 m.
Using the formula for circumference C = 2πr:
8.8 m = 2 * (22/7) * r
8.8 = (44/7) * r
r = (8.8 * 7) / 44 = (88/10 * 7) / 44 = (2 * 44 / 10 * 7) / 44 = (2/10) * 7 = 0.2 * 7 = 1.4 meters.
Converting meters to centimeters: 1.4 meters * 100 cm/meter = 140 cm.
However, 140 cm is not among the options. Let’s re-check the calculation assuming the distance was 4.4 km instead of 44 km, as the options are relatively small values in cm.
If distance = 4.4 km = 4400 m.
Circumference C = 4400 m / 5000 = 44/50 m = 22/25 m = 0.88 m.
Using C = 2πr:
0.88 m = 2 * (22/7) * r
0.88 = (44/7) * r
r = (0.88 * 7) / 44 = (88/100 * 7) / 44 = (2 * 7) / 100 = 14/100 = 0.14 meters.
Converting meters to centimeters: 0.14 meters * 100 cm/meter = 14 cm.
This matches option A. Given the options, it is highly probable that the intended distance in the question was 4.4 km, not 44 km.