# Solution to #1-2

Paper 2 Difficulty: Medium

A ball is thrown in the air and 5 different students are individually measuring the time it takes to fall back down using stopwatches. The times obtained by each student are the following:
6.2 s, 6.0 s, 6.4 s, 6.1 s, 5.8 s

a) What is the uncertainty of the results?

[Maximum mark: 2]

The range is $6.4-5.8=0.6$ s and the uncertainty is half the range, so the answer is $\pm 0.3$ s.

b) How should the resulting time be expressed?

[Maximum mark: 1]

The mean of the values obtained by the 5 students is:
$\frac{6.2+6+6.4+6.1+5.8}{5}=\frac{30.5}{5}=6.1$
Therefore the time should be expressed as $6.1\pm 0.3$ s.