Accuracy and Measure

Accuracy and Measure

Mr. Underwood

Lesson objectives:

• To be able to convert between measurements

• To be able to calculate compound measurements to a required accuracy

• To be able to calculate upper and lower bounds of error

Converting Measures

The following conversions need to be memorised for GCSE

Multiple Choice

Convert 20cm into mm

• 2 mm

• 40 mm

• 200 mm

• 20 mm

Multiple Choice

The weight capacity of a bridge is 3000kg. A truck weighing 2.7 tonne is trying to cross. Will the bridge be able to hold the weight?

• Yes

• No

Compound measures describe how one quantity changes in proportion to another

• the units for a compound measure are of the form x / b (e.g speed is measured in m/s)

• be careful of what units the question wants the final answer in (you may have to convert measurements!)

Measurements are not exact. Their accuracy depends on the precision of various factors (equipment, human error ... e.t.c)

• Look at the smallest place value in the measurement (e.g 0.1)

• Half that value to get the error (e.g 0.05)

• Add and take away the error to find the upper and lower bound (127.3 + 0.05 127.3 - 0.05)