(a) A rectangular field is l metres long and b metres wide. Its perimeter is 280 metres. If the length is two and a half times the breadth, find the values of l and b.
(b) The base of a pyramid is a 4.5 metres rectangle. The height of the pyramid is 4 metres. Calculate its volume.
Explanation
(a) Perimeter of a rectangle = 2(l + b)
(2l + 2b = 280)
But l = 2.5b,
(2(2.5b) + 2b = 280 implies 7b = 280)
(b = 40 m)
(therefore l = 2.5(40) )
= (100 m)
(b) Volume of pyramid = (frac{1}{3}l times b times h)
= (frac{1}{3}(4.5) times 2.5 times 4 )
= (15 m^{3}).