A lift and its passengers have a mass of 1000 kg…

Step 1. Tension. $T = 1000\ \text{kg} \times (9.8\ \text{m/s}^2 + 1.2\ \text{m/s}^2) = 11\,000\ \text{N}$.

Step 2. Area. $\dfrac{7 \times 11\,000\ \text{N}}{4.5 \times 10^{8}\ \text{Pa}} = 1.71 \times 10^{-4}\ \text{m}^2$.

Step 3. Radius. $r = \sqrt{\dfrac{1.71 \times 10^{-4}\ \text{m}^2}{\pi}} = 7.38 \times 10^{-3}\ \text{m}$.