Maths / Comparing Quantities / Percentage Change

QUESTION

If radius of a circle is increased by 50% then area of the circle will be increased by

 OPTIONS A. 50% B. 150% C. 125% D. 200%
Right Option : C

EXPLANATION
Explain TypeExplanation Content
Text

$50X2=100\\\\5.0X5.0=\frac{25}{125}$

or

Let the radius = r

increase = 50% of r=0.5r

New Radius = 1.5r

$\dpi{120} \fn_jvn \large Original\: Area = \pi X r^2$

$\dpi{120} \fn_jvn \large New\: Area = \pi X (1.5r)^2 = 2.25\pi Xr^2$

$\dpi{120} \fn_jvn \large Increase= 2.25\pi Xr^2 -\pi X r^2 = 1.25\pir^2$

$\dpi{120} \large Percentage \: Increase= \frac{increase}{original}X 100=\frac{1.25\pi r^2}{\pi r^2} X 100$

$\dpi{120} \large = 125$

View Contents
(Concept based Learning and Testing for [6th - 10th], NTSE, Bank & Govt. Exams)
Self Learning
Testimonials
PARENT RESPONSE c/o Hiya Gupta C/o ABHYAS Academy
9th
My experience with abhyas is very good. It had helped to increase mental ability of my ward.

#### Other Testimonials

Courses We Offer
(Concept based Learning and Testing for [6th - 10th], NTSE, Bank & Govt. Exams)