©G Dear 2010 – Not to be sold/Free to use Applied Mathematic (Preliminary General 1) Measurement Managing Error Stage 6 - Year 11 Press Ctrl-A ©G Dear 2010 – Not to be sold/Free to use

Measure! Measure! Measure! Reducing Error When objects are measured their is always some amount of error. To reduce the error we must . . . Measure! Measure! Measure!

Blood Pressure Measure your blood pressure three times. Reject the extreme value. Average the other readings. Systolic Diastolic 156 80 132 70 136 50 Sys = (132+136) ÷ 2 = 134 Dia = ( 70 + 80) ÷ 2 = 75

Measuring Area Get 3 students to measure the dimensions of a book in cm. (Enter in table above.) Soft Keyboard

Actual Length lies between Degree of Accuracy All measurements are accurate to within ± 0.5 of the smallest unit on the measuring device. = 4 cm Error = ±0.5 cm Actual Length lies between 4 + 0.5 = 4.5cm 4 – 0.5 = 3.5cm

What decree of accuracy would be needed when measuring a … ? Degree of Accuracy What decree of accuracy would be needed when measuring a … ? a) Lighthouse b) Soccer ball metres centimetres

Degree of Accuracy Between what two limits does 75m lie if measured with a trundle wheel to the nearest metre? Error = ±0.5 m Lower = 75 - 0.5 = 74.5 m Upper = 75 + 0.5 = 75.5 m

Degree of Accuracy Between what two limits does 360cm lie if measured with a decimetre tape to the nearest 10cm? Error = ± 5 cm Lower = 360 - 5 = 355 cm Upper = 360 + 5 = 365 cm Decimetre tape

Degree of Accuracy Between what two limits does 500 km lie if measured with a odometer to the nearest 5km? Error = ± 2.5 km Lower = 500 - 2.5 = 497.5 km Upper = 500 + 2.5 = 502.5 km Odometer

Degree of Accuracy A building’s height was measured as 93 metres to the nearest metre. Between what limits does it lie? Range = 93 ± 0.5 metres Between 92.5m and 93.5 m.

Degree of Accuracy A ball was measured as 80cm to the nearest 10cm. Between what limits does it lie? Range = 80 ± 5cm Between 75cm and 85 cm.

Degree of Accuracy The distance from Port Macquarie to Sydney is given as 500km to the nearest 100km. Between what limits does it lie? Range = 500 ± 50km between 550km and 650km.