Question

will measures the diameter of a penny as 1.9 cm using the ruler what is the margin of error

Answer 1

he is off by a little 

Answer 2

Diameter of Penny measured by Will using the ruler=1.9 cm

The exact measurement of Penny's Diameter can't be 1.9 cm, it can be in between [1.85 cm , 1.90 cm) or (1.90 cm,1.95 cm].

→Margin of error will be

        Between, 0 cm to 0.05 cm.

That is→ (0,0.05).