Question

6(c). The cost (c) of producing n bricks is the sum of a fixed amount, h, and a variable amount, y, where y varies directly as n. If it costs GH₵950.00 to produce 600 bricks and GH₵1,030.00 to produce 1000 bricks: (i) find the relationship between c, h and n; (ii) calculate the cost of producing 500 bricks.

Accepted Answer

(i) c = h+kn where y=kn. From the data: 950=h+600k and 1030=h+1000k. Subtracting: 80=400k, so k=1/5=0.2. Then h=950−600(0.2)=950−120=830. So c = 830+0.2n (or c=h+n/5, with h=830 GH₵).
(ii) When n=500: c = 830+0.2(500) = 830+100 = GH₵930.00.

WAEC Mathematics 2015 Theory — Question 11

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