Both are precise, but in different contexts.
An ounce is a smaller measure so 6 oz has a greater absolute precision. On the other hand, 320 is accurate to 2 significant figures so 320 lbs has greater relative precision.
What determines how precise a measurement is
It is precise if it is repeatable.
Is as exact as possible
tenth of a gram
The precise measurement is 5.7 mm for the first value and 3.6 m for the second value.
No. An answer is only as precise as the least precise measurement from which it was calculated.
What determines how precise a measurement is
It is precise if it is repeatable.
You can make a very precise measurement with a poorly calibrated device.
No. Accurate relates to how close the actual measurement the instrument measures. Precise relates to how much detail the instrument gives when measuring. They are independent to each other: An measurement can be precise and accurate (eg the value of π is 3.141592654) An measurement can be precise and inaccurate (eg the value of π is 1.733677432) An measurement can be less precise and accurate (eg the value of π is 3.14) An measurement can be less precise and inaccurate (eg the value of π is 1.73).
measuring tape
320lb = 145.1kg
19.2cm is more precise
An automatically measurement has a higher precision than a manually measurement.
Is as exact as possible
tenth of a gram
A measurement in pints is more precise.