An aluminium plate is a rectangle measuring 25cm by 18cm. Three identical circular holes, each of diameter 4cm, are drilled along the longer side at equal spacing.
a. (a) Calculate the total area removed by the three circular holes.
b. (b) Determine the area of aluminium left in the plate after the holes are drilled.
c. (c) The plate is 0.4cm thick and the density of aluminium is 2.7g cm−3. Find the mass (in grams) of the remaining plate, correct to one decimal place.