If the radius of a circle is decreased by 50%, its area is reduced by :

a. 25%
b. 50%
c. 75%
d. None

• 
  ANS:-75%
  if any sides of 1 rectangle,sphere,circle,rhombus,square increase by x5 then used the formula 2x+(x2/100)% AND by decreased by x% then 2x-x2/100
  so in this case, radis decreased by 50%
  2*50-(50*50)/100
  100-25
  75%
• 12 years agoHelpfull: Yes(4) No(0)
• ans.9.75%
  radius is decreased by 50%
  so,new radius r'=r+dr=r-0.5r=0.95r
  area=pi*r^2
  new area is a'
  therefore.
  a'=a*[(pi*r^2)/(pi*(0.95r)^2)]
  a'=0.9025a
  a'=a-0.0975a
  da=0.0975=9.75%
• 9 years agoHelpfull: Yes(0) No(1)