Question

What is the greatest possible error when measuring to the nearest quarter of an inch? 1/8 in. 1/4 in. 1/2 in.

Answer 1

The greatest possible error is one half of the measuring unit you're using.

Multiply the unit you use by 1/2:

$\frac{1}{4} * \frac{1}{2} = \frac{1}{8}$

The greatest possible error will be 1/8 inch.

Answer 2

The farthest away you can be from the appropriate 1/4 inch mark is
   1/8 in.