Measurement, Errors, Data and Unit Conversion

Zeroing error because in this example, the object being measured is not aligned with the start of the measuring scale.

You know that 1″ is the same as 2.54 cm, so ten of them would be 10 × 2.54 = 25.4 cm. Hence 40 of them would be 40 × 2.54 = 110.6 cm.

An accuracy of ±0.005% means that for a displayed reading of 0.055%, the actual value may be as low as 0.055–0.005 = 0.05% or as high as 0.055 + 0.005 = 0.06%, hence will be between 0.05% and 0.06%. To ensure that the actual % blood alcohol concentration is in fact above 0.05%, the reading should be more than 0.005 above the limit of 0.05%.

Both the SI system and the Australian Metric System are “metric”; the mmHg is not (despite having millimetre in its name).

As the words suggest, random error is not systematic as it is unpredictable.

An actual value of 37.76 °C would be seen on a scale that has 0.1 as its smallest interval, as 37.8. All other values are closer to 37.7 than they are to 37.8 or to 37.6.

The number of “+” signs indicates a level of magnitude that is semiquantitative, but there is no unit of magnitude. C is “qualitative”, while D is “nominal”.

Centigrade temperature values above zero are always smaller than Fahrenheit values. T(°C) = (T(°F) – 32) × 5/9 = (101–32) × 5/9 = 69 × /9 = 345/9 = 38.3 °C.

Micro refers to “a millionth of”. There are 1.25 × 106 millionths of a gram in 1.25 g, so 1,250,000 millionths of a gram = 1,250,000 micrograms (g to μg: shift the decimal point six places to the right).

1000 μg is needed to make a milligram, so we have less than one (μg to mg: shift the decimal point three places to the left).Note: The following three questions about the “central tendency” of data rely on the following information. Consider the weekly earnings in dollars for ten workers to be 400, 475, 475, 475, 500, 500, 525, 620, 630 and 660. These ten wages add to the total of $5260.