Question

The approximate change in the volume of a cube of side x metres caused by increasing the side by 3% is

• A. 0.06 x3 m3
• B. 0.6 x3 m3
• C. 0.09 x3 m3
• D. 0.9 x3 m3

Answer 1

Answer: (C)

0.09 x3 m3

Answer 2

The volume of a cube (V) of side x is given by V =x3

$\frac{dv}{(\frac{dv}{dx})}$Δx

=(3x2)Δx

=(3x2)(0.03x) [As 3% of x is 0.03]

=0.09x3m3

Hence, the approximate change in the volume of the cube is 0.09x3 m3.

The correct answer is C.