Theory question 101
Fractions, Decimals and Approximation(a) Evaluate, without using mathematical tables or calculator, (3.69 × 105) ÷ (1.64 × 10−3), leaving your answer in the standard form.
(b) A man invested N20,000 in bank A and N25,000 in bank B at the beginning of a year. Bank A pays simple interest at a rate of y% per annum and B pays 1.5y% per annum. If his total interest at the end of the year from the two banks was N4,600, find the value of y.
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Model answer
(a) 3.69 ÷ 1.64 = 2.25 and 105 ÷ 10−3 = 108, so the answer is 2.25 × 108.
(b) Interest from A = 20,000 × y/100 = 200y; from B = 25,000 × 1.5y/100 = 375y.
200y + 375y = 4600, so 575y = 4600 and y = 8.
Explanation
Divide the numbers and subtract the powers of 10 separately.