Which of the following is precise given that the accepted value is 5.345 and the observed values are 3.253, 3.45, and 3.732?

3.253
3.457
3.732
all of the above
none of the above

[multiple choice] if given an accepted value of 5.95 m and three observed values of 5.73 m, 5.90 m, and 5.95 m, the observed value of 5.90 m

is accurate.
is precise.
has only two significant digits.
has at least one digit that is not significant.
has a percent error of −0.8%.
is equivalent to 5.90 109 nm.
has a derived si unit.

and explanation for these too.. and you! i'd really love to understand these.