1. Review of Essential Skills:
Accuracy vs. Precision

2. Calculations Involving Measured Quantities
The accuracy of a measured quantity is based on the measurement tool.
The last digit always represents a guess.
Rule: When making measurements, estimate your measure to the closest tenth of the smallest scale.

3. Consider a line of length 5.85 cm using the ruler below:
The final digit of 5.85 cm is an estimate of the nearest tenth of the scale.
Using our rounding rule >> 5.85 cm = 5.8 cm
Therefore our answer is accurate to 2 sig figs where “.8” is the least reliable digit.

4. Accuracy vs. Precision
Accuracy: The number of significant digits within a measured quantity.
Precision: The smallest scale of the measurement represented by the last significant digit.

5. Eg.1: For each value below determine
The number of significant figures
The accuracy of the value
The precision of the value
Value
I = cm
y = 240 m
z = x 10-2 m a) b) c) 5 2 4
I accurate to 5 sig figs
y accurate to 2 sig figs
z accurate to 4 sig figs
I precise to 10-4 cm
y precise to 10 m
z precise to 10-5 m

6. Operations & Measured Quantities
Addition & Subtraction (precision-based)
Answer is expressed with same precision of least precise quantity.
Multiplication & Division (accuracy-based)
Answer is expressed with same accuracy of least accurate quantity.

7. Eg. 2: Find the total volume for the following quantities: 95 mL, 3
Eg.2: Find the total volume for the following quantities: 95 mL, 3.27 mL and 2.10 mL
Eg.3: Find the perimeter for the following scalene triangle: cm, 2.1 m, 5 cm
Eg.4: Add the following time intervals: s, 4.5 s, 0.05h.
Eg.5: Find the volume of the box with the following dimensions: l = 2.1 cm, w=2.01 cm, h = 1.09 cm