Identical cylindrical tins of radius 7 cm and height 40 cm are packed upright inside a cardboard carton whose internal dimensions are 50 cm × 40 cm × 45 cm.
a. (i) Determine the maximum number of tins that can be accommodated in one carton.
b. (ii) Calculate the volume of unused space left in the carton after packing the tins.
c. (iii) The unused space is filled with protective foam costing Rs 0.60 per cm³. Find the cost of the foam required for one carton.