Say you made three different mass measurements of a sugar cube. You know the mass is 1.0g. how would you know whether or not the measurements were accurate? Precise?

Answer 1

Suppose you weighed the cube and obtained the following:
0.50 g; 1.0 g; 1.50 g
The average is 1.00 g; therefore, the accuracy is very good but the precision is lousy.

Suppose you weighed the cube and obtained the following:
0.50 g; 0.51 g; 0.49 g.
The average is 0.50 g which is far from the actual value of 1.0 g; therefore, the accuracy is lousy but the precision is good.

Suppose the weighings were as follows:
0.50 g; 0.60 g; 0.70 g.
The accuracy is not good (its a long way to 1.0 g) AND the precision is not good either.

The fourth case is the last possibility.
0.99 g; 1.0 g; 1.1 g.
The average is 1.0 g; therefore, the accuracy is very good and the precision is very good.