Question

A bicycle wheel makes 5000 revolutions in moving 11 km. what is the radius of the wheel? 1)40cm2)15cm3)35cm4)25cm

Answer 1

Given,
no. of revolutions=5000
distance travelled=11km=1100000 cm
We know,
Circumference=distance travelled/ no. of
revolutions made
=1100000/5000
=220 cm.
Let the radius be r.
Accordingly,
2πr=220
=>2*(22/7)*r=220
=>r=(220*7)/(22*2)
=>r=35 cm.
Hence,the answer is 3)

Answer 2

Solution :


Let the radius of bicycle be 'x' and Distance covered by Bicycle.



Distance covered by Bicycle in 1 Revolution = Distance covered / Total Number of revolution

✒ Distance covered by Bicycle in 1 Revolution = 11/ 5000 km

= 11/5000 × 1000 × 100 cm

= 11/5 × 100 cm

= 11× 20 cm

= 22,0 cm

✍We have Circumference of Circle = 220 cm

✒ Circumference of Circle = πD

✒ Circumference of Circle = 22/7 × D

✒ 22,0 = 22/7 × D

✒ 22,0 × 7 = 22D

✒ 1540 = 22D

✒ Diameter = 70 cm

✒ Radius = 35 cm

Therefore, Radius is 70 cm.