Question

Calculate the answer for the following question and state the answer with the correct certainty and units.

Given the values of b and h, find A.
b=3.2 cm, h=10.1 cm
A=1/2bh

The answer is 16 cm^2, which was rounded to two significant digits from 16.16 cm^2,because 3.2 has a certainty of 2 significant digits and 10.1 has a certainty of 3 significant digits. But 1/2 is 0.5, and that has a certainty of only 1 significant digit, so shouldn't the answer have only 1 significant digit?

Answer 1

One half is exact. It is part of the formula, not data that is only known to some accuracy.

Answer 2

Oh, okay thanks!