Sachin Tendulkar while walking diametrically across a semicircular playground, takes 3 minutes less than if he had kept walking round the circular path from A to B. If she walks 60 metres a minute, What is diameter of the play ground ?
Please Explain the answer!

• 315 mtr
  
  If r is radius of semicircle ground, then
  2r/60 = (Pi*r/ 60)-3
  solving, D=2r = 315 mtrs
• 11 years agoHelpfull: Yes(2) No(1)
• Diameter=315 m.
  Let R=radius of circular path and given Speed=60*60=3600 m=3.6 km/hr
  Distance travelled Diametrically=2R, and through circular path=Pi*R
  Given time of 3 minutes (=1/20 hr.) less in covering both these distance
  So (Pi*R-2R)/3.6 =1/20 or R(Pi-2)=3.6/20, R=0.1575 Km
  Therefore Diameter=2R=2*0.1575=0.315 km. or 315 meters
• 11 years agoHelpfull: Yes(1) No(1)
• Suppose radius is 'R'.(in meter)
  Speed =60 m/min.
  Time to reach from point A to B (Diametrically)=2R/60
  Time to reach from point A to B(using other path)=(2*3.14*R)/60.
  Given-
  (2*3.14*R)/60-2R/60=3.
  after solving 2R=315 meter.
  
• 11 years agoHelpfull: Yes(0) No(1)