Question

A quality control officer is randomly checking the weights of flour bags being filled by an automatic filling machine. Each bag is advertised as weighing 900 grams. A bag must weigh within 1.7 grams in order to be accepted. What is the range of rejected bags, x, for the bags of flour?

Answer 1

Bags are rejected for |x-900| > 1.7

... -1.7 > x - 900 > 1.7 . . . . . . . . . a slightly improper way to write the unfolded inequality. To be absolutely correct, this would be written as two inequalities. Ignoring that detail, this is useful to see that the solution is found by adding 900.

... (898.3 > x) ∪ (x > 901.7) . . . . . . will cause rejection