Question

ram goes for a morning walk in a circular park daily he completes 1 revolution of the park in 4m.Find out his speed if the diameter of the park is 420m.

Answer 1

Given , diameter of the circular park is 420m
We know that circumference of a circle = π × diameter 
 ⇒22/7 ×420
 ⇒1320. 
Therefore distance = 1320m
Given time = 4 min = 4 × 60 sec = 240 sec
Now , speed = distance / time = 1320/240 =  5.5 m/sec 
 

Answer 2

DIAMETER = 420 m
 RADIUS = 420 / 2 = 210 m
DISTANCE COVERED IN 1 REVOLUTION = CIR. OF CIRCLE
                                                                = 2 * 22/7 * r
                                                                = 44/7 * 210
                                                                 = 1320 m

TIME TAKEN = 4 minutes = 4 * 60 s = 240 s

 SPEED  = DISTANCE / TIME
               = 1320 / 240 
               = 5.5 m/s