Tyre of a bicycle has volume \(2 \times 10^{-3} \mathrm{~m}^3\). Initially, the tube is filled \(75 \%\) of its volume by air at atmospheric pressure \(10^5 \mathrm{Nm}^{-2}\). When a rider is on the bicycle, the area of contact of tyre with road is \(24 \times 10^{-4} \mathrm{~m}^2\). The mass of rider with bicycle is \(120 \mathrm{~kg}\). If a pump delivers a volume \(500 \mathrm{~cm}^3\) of air in each stroke, then the number of strokes required to inflate the tyre is \(\left(g=10 \mathrm{~ms}^{-2}\right)\)

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.