1.	Define- Accuracy; Tolerance; Precision; Uncertainty.

Accuracy is when the measured value is very close to the accepted value. 
Tolerance is the most accurate measurement that one can measure using an instrument. 
Precision is the closeness or exactness among a group of measurements.
Uncertainty is when you cannot tell exactly where the measurement lands. It is impossible to measure an object exactly so you can express this uncertainty by using +/-