Question

The measurement of the radius of a circle has an error of 1%. The error in measurement of its area is (A) is:

• A. 1%
• B. 2%
• C. 3%
• D. none of these

Answer 1

The correct option is B 2%

Error in radius measurement $\frac{\Delta r}{r}\times 100=1$%
Area of the circle is given by $A=\pi r^2$
So, error in area $\frac{\Delta A}{A}\times 100=2\times \frac{\Delta r}{r}\times 100=2$%