Completion times are recorded to the nearest second. In a histogram, the bar for the class 5–85\text{–}85–8 has height 3 units and the bar for the class 11–1511\text{–}1511–15 has height 2 units.
Time (s)1–45–89–1011–1516–20Frequency2128?3\begin{array}{c|ccccc}\text{Time (s)}&1\text{–}4&5\text{–}8&9\text{–}10&11\text{–}15&16\text{–}20\\\hline\text{Frequency}&2&12&8&?&3\end{array}Time (s)Frequency1–425–8129–10811–15?16–203
Use the relative bar areas to find the missing frequency.
Calculate the frequency densities for the remaining three classes.
Estimate the probability that a randomly selected participant took under 10 seconds.
105 exam-style questions on WJEC A Level Maths 2.2 Data presentation and interpretation, covering 2.2.1 Data presentation and interpretation, 2.2.2 Data presentation and interpretation, 2.2.3 Data presentation and interpretation, 2.2.4 Data presentation and interpretation, 2.2.5 Data presentation and interpretation, 2.2.6 Data presentation and interpretation, 2.2.7 Data presentation and interpretation, 2.2.8 Data presentation and interpretation, and 2.2 Data presentation and interpretation. Each one has a worked solution and a mark scheme showing where the marks go.