(i) From the cumulative frequency graph, determine the lower quartile (LQ), median, and upper quartile (UQ):

• LQ = 15 (thousands of euros)
• Median = 18 (thousands of euros)
• UQ = 26 (thousands of euros)

Draw a box-and-whisker plot with these values, using a linear scale from 0 to 80 (thousands of euros). The whiskers extend from the minimum (5) to LQ and from UQ to the maximum (80).

(ii) Comment: Most (3/4) of the sample earn less than 26,000 euros, indicating not many earn high salaries.

(iii) Calculate the interquartile range (IQR):

\(\text{IQR} = UQ - LQ = 26 - 15 = 11\)

(a) A high outlier is any salary above:

\(UQ + 1.5 \times \text{IQR} = 26 + 1.5 \times 11 = 42.5 \text{ (thousands of euros)} = 42500 \text{ euros}\)

(b) A low outlier is any salary below:

\(LQ - 1.5 \times \text{IQR} = 15 - 1.5 \times 11 = -1.5 \text{ (thousands of euros)}\)

Since the lowest salary is 5000 euros, no salaries are low enough to be classified as outliers.