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WAEC 2021 · Paper 2 · Q9

  1. (a)

    An aircraft XX leaves airport PP at 09:55 hours GMT and arrives at airport QQ at 14:15 hours GMT. Given that the distance between the two airports is 2210 km2210\text{ km}, find the: (i) flight time; (ii) speed of the aircraft XX.

  2. (b)

    Two years ago, a farmer purchased a machine for use in his farm. If the machine depreciates at an annual rate of 812%8\frac12\% and the current value is ₦102,500.00, find, correct to the nearest naira, the value of the machine: (i) after the third year of the purchase; (ii) when it was purchased.

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

Worked solution (try it first)

(a)(i)

  1. From 09:55 to 14:15 is 4 hours 20 minutes, which is 4134\frac13 hours.

(ii)

  1. Speed =2210413= \frac{2210}{4\frac13}
    =2210×313= 2210 \times \frac{3}{13}
    =510= 510 km/h.

(b)

  1. Each year the value is multiplied by 1−0.085=0.9151 - 0.085 = 0.915.

(i)

  1. After the third year: one more year from now, 102 500×0.915=93 787.5102\,500 \times 0.915 = 93\,787.5, which is ₦93,788 to the nearest naira.

(ii)

  1. Two years ago it was worth 102 5000.9152=102 5000.837225\frac{102\,500}{0.915^2} = \frac{102\,500}{0.837225}
    ≈₦122,428\approx ₦122,428.

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