Write down the median age.

Find the interquartile range for the ages.

Given that the youngest teacher is $21$ years old and the oldest is $72$ years old, represent the information on a box and whisker plot using the scale below.

${\text{Median }}= 45$     (A1)     (C1)

Accept $45.5$

[1 mark]

$53 - 37$ for identifying correct quartiles     (A1)
$= 16$ for correct answer to subtraction     (A1)(ft)     (C2)

(ft) on their quartiles

[2 marks]

Median marked correctly.     (A1)(ft)
Box with ends at candidate’s quartiles.     (A1)(ft)
End points at $21$ and $72$ joined to box with straight lines.     (A1)     (C3)

Note: Award (A0) if lines go right through the box.

[3 marks]

Accuracy reading the graph in part (a) was a problem with little allowance given. A number read the maximum as $130$ instead of $120$.

Part (b) was poorly done. Many candidates did not know how to find the quartile values from the graph.

Accuracy reading the graph in part (a) was a problem with little allowance given. A number read the maximum as $130$ instead of $120$. Part (b) was poorly done. Many candidates did not know how to find the quartile values from the graph. Many candidates gained follow through marks for the box and whisker plot by writing down their values for part (b). Some candidates did lose a mark for drawing the whiskers through the box.