If the radius of a cylinder is decreased by 8%, while its height is increased by 4%, what will be the effect on volume?

Here, A = -8%, B = 4%
According to the formula,
Net effect on volume = [2A + B + A² + 2AB/100 + A²B/100²]%
= [2 x (-8) + 4 + (-8)² + 2 x (-8) x 4 /100 + (-8)² x 4 /100²]
= [-16 + 4 + 64 - 64/100 + 256/10⁴]%
=[-12 + 0 + 0.0256]%
= -11.9744% (decrease)