Question

1. Select the most precise experimental result for the Earth's circumference, which is 40075 km.

a) 40100 ± 100 km

b) 40080 ± 25 km

c) 40000 ± 100 km

d) 40090 ± 50 km

e) 40000 ± 20 km

2. Select the most accurate experimental result for the Earth's circumference, which is 40075 km.

a) 40100 ± 100 km

b) 40080 ± 25 km

c) 40000 ± 100 km

d) 40090 ± 50 km

e) 40000 ± 20 km

Answer 1

"Accuracy" of result of a measurement refers to how close are the measured values to the true known values. The closer the measured values are to the true known value, more accurate they are.

"Precision" of a measurement results describes how close are the measured values to each other. The closer the measured values are of each other, better the precision. True value known or not, doesn't matter.

Here in the e) 4000020 km result, all the measured values are the closest to each other, so this is the most precise one. However note that this is not very accurate.

The measurement b)4008025 km although less precise than e), has the closest average value to the true known value of 40075 km. So it's the most accurate one.