The table below shows the results of an investigation showing the smoking habits of men aged 40 – 79 and the number that die from lung cancer.

• Non-smoker: $\frac{10}{247} \times 100\% \approx 4.05\%$
• Cigar only: $\frac{20}{247} \times 100\% \approx 8.10\%$
• Pipes only: $\frac{22}{247} \times 100\% \approx 8.91\%$
• Mixed: $\frac{85}{247} \times 100\% \approx 34.41\%$
• Cigarette smoker: $\frac{110}{247} \times 100\% \approx 44.53\%$

• Non-smoker: $\frac{10}{247} \times 360^\circ \approx 14.57^\circ$
• Cigar only: $\frac{20}{247} \times 360^\circ \approx 29.15^\circ$
• Pipes only: $\frac{22}{247} \times 360^\circ \approx 32.06^\circ$
• Mixed: $\frac{85}{247} \times 360^\circ \approx 123.72^\circ$
• Cigarette smoker: $\frac{110}{247} \times 360^\circ \approx 160.50^\circ$

The calculations for the pie chart are:

• Non-smoker: $4.05\%$ ($14.57^\circ$)
• Cigar only: $8.10\%$ ($29.15^\circ$)
• Pipes only: $8.91\%$ ($32.06^\circ$)
• Mixed: $34.41\%$ ($123.72^\circ$)
• Cigarette smoker: $44.53\%$ ($160.50^\circ$)

3.1.2

Two ways to increase the reliability of the investigation are:

• Increase the sample size (study more men).
• Repeat the investigation multiple times and compare the results.

3.1.3

Two factors kept constant in the investigation are:

• The age range of the men (40-79 years).
• The gender of the participants (men).

3.1.4

The habit with the least influence in causing death from lung cancer is Non-smoker, with 10 deaths per 100 000.

3.1.5

• Deaths for cigarette smokers = 110
• Deaths for non-smokers = 10

A cigarette-smoker is $\boxed{\text{11 times}}$ more likely to die of lung cancer than a non-smoker.

3.1.6

Cilia are tiny hair-like structures that sweep mucus and trapped particles out of the breathing tract. When smoking destroys cilia, mucus and harmful substances accumulate in the airways, leading to increased risk of infections, chronic cough, and respiratory diseases.