Which quantity in a given formula should be measured most accurately Why?

In determing viscosity (eta) by poiseuille's method for formula used eta = (pi p r^4)/(8 vl) . Which of the quantities in the formula must be measured more accurately

In determing viscosity (eta) by poiseuille's method for formula used eta = (pi p r^4)/(8 vl) . Which of the quantities in the formula must be measured more accurately

The period of oscillation of a simple pendulum is given by T=2pi sqrt((l)/(g)) . In finding the value of g, which quantity should be measured most accurately and why?

The modulus of rigidity of a wire is given by the formula W_(g)=(npir^(4)theta)/(2l) . Which of these quantities should be measured very accurately and why?

Why quantities appearing with higher (power) exponent should be measured with most accurately ?