Q. 113.9( 19 Votes )
The time which took today my friend Rajat running with uniform speed to round once of a circular field of school is 30 seconds less while he ran diametrically with same speed. Let us write by calculating the area of field of school if his speed is 9 meter/sec.
Answer :
Given, speed of Rajat = 9 m /sec
Where distance is the perimeter of circular field
But perimeter = 2π r where r is the radius of circle
⇒ Time taken =
According to the given condition
Where r is radius of circular field and 2r = diameter
⇒
⇒ 2π r – 270 = 2r (taking LCM and cancelling 9 from both side)
⇒ 2π r – 2r = 270
⇒ r (π -1) = 135
⇒ 
Area of the circular field = πr2 where r is the radius
=
m2
= 12474 m2
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