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WAEC 2017 · Paper 2 · Q6

  1. (a)

    A manufacturing company requires 3 hours of direct labour to process every ₦87.00 worth of raw materials. If the company uses ₦30,450.00 worth of raw materials, what amount should it budget for direct labour at ₦18.25 per hour?

  2. (b)

    An investor invested ₦xx in bank MM at the rate of 6%6\% simple interest per annum and ₦yy in bank NN at the rate of 8%8\% simple interest per annum. If a total of ₦8,000,000.00 was invested in the two banks and the investor received a total of ₦2,320,000.00 as interest from the two banks after 4 years, calculate the: (i) values of xx and yy; (ii) interest paid by the second bank.

    Separate values with commas, e.g. 3, −2

Worked solution (try it first)

(a)

  1. Every ₦87.00 of raw materials needs 3 hours.
  2. ₦30,450.00 is 30 45087=350\frac{30\,450}{87} = 350 lots of ₦87.00.
  3. So the labour needed is 350×3=1050350 \times 3 = 1050 hours.
  4. At ₦18.25 an hour, the budget is 1050×18.25=1050 \times 18.25 = ₦19,162.50.

(b)(i)

  1. Simple interest =principal×rate×time100= \frac{\text{principal} \times \text{rate} \times \text{time}}{100}.
  2. In 4 years, bank MM pays x×6×4100=0.24x\frac{x \times 6 \times 4}{100} = 0.24x and bank NN pays y×8×4100=0.32y\frac{y \times 8 \times 4}{100} = 0.32y.
  3. Two facts give two equations: x+y=8 000 000x + y = 8\,000\,000 (1) and 0.24x+0.32y=2 320 0000.24x + 0.32y = 2\,320\,000 (2).
  4. Multiply (1) by 0.24: 0.24x+0.24y=1 920 0000.24x + 0.24y = 1\,920\,000 (3).
  5. Take (3) from (2): 0.08y=400 0000.08y = 400\,000, so y=5 000 000y = 5\,000\,000.
  6. Then x=8 000 000−5 000 000x = 8\,000\,000 - 5\,000\,000
    =3 000 000= 3\,000\,000.
  7. So x=x = ₦3,000,000.00 and y=y = ₦5,000,000.00.

(ii)

  1. Bank NN paid 0.32×5 000 000=0.32 \times 5\,000\,000 = ₦1,600,000.00 in interest.

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