Max/Min error Mathematics problem

Question

Given an equation R = PQ, whereby P and Q has a max error of 2% and 5% respectively, what is the maximum positive and maximum negative error of R?

Answer

Max:

R = 1.02P * 1.05Q = 1.071PQ
Max % = (1.071 - 1) * 100 = 7.1%

Min:

R = 0.98P * 0.95Q = 0.931PQ
Min % = (0.931 - 1) * 100 = -6.9%