r = 35 cm = \( \Large \frac{35}{100000}km \)
Now the distance covered in 1 revolution = \( \Large 2 \times \pi \times r \)
= \( \Large 2 \times \frac{22}{7} \times \frac{35}{100000} = \frac{220}{10000}\) = \( \large \frac{22}{100000}km \)
In 500 revolutions,
Distance covered = \( \Large 500 \times \frac{22}{10000} km \)
= \( \Large \frac{22}{20}km \) = \( \frac{11}{10}km \)
So \( \Large \frac{11}{10}\) km is covered in 1 minute.
60 min = 1 hr, distance covered
=\( \Large \frac{60 \times 11}{10}km \)
= 66 km
Hence, speed = distance/time
= 66km / 1 hr = 66 Km/hr