Theory question 107
Commercial Arithmetic(a) A radio which a dealer bought for N6,000.00 and marked to give a profit of 30% was reduced in a sale by 10%. Find (i) the final sale price (ii) the percentage profit.
(b) Solve the equation 2(2x+1) − 9(2x) + 4 = 0
Show the model answer
Model answer
(a)(i) Marked price = 130% of N6,000 = N7,800. Sale price = 90% of N7,800 = N7,020.
(ii) Profit = 7,020 − 6,000 = N1,020; percentage profit = 1020/6000 × 100% = 17%.
(b) 22x+1 = 2(2x)2. Let y = 2x: 2y2 − 9y + 4 = 0, (2y − 1)(y − 4) = 0.
y = ½ or 4, so 2x = 2−1 or 22: x = −1 or x = 2.
Explanation
Percentage profit is always worked out on the cost price.