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Business Mathematics
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Final examination / assessment, as stated in the official syllabus. Ask a senior or your exam office for a past paper to confirm the question pattern.

Graded A+ (85-100) to E (0-24) on a 12-step scale; GPA is credit-weighted (5 credits per course unit).

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Likely questions

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Structured problems
Solve 3x + 2y = 18 and 5x − 2y = 14, and check your answer.Unit ISolve 3x² − 5x − 2 = 0 by factorising, and confirm with the quadratic formula.Unit IUsing logarithms, find how many years Rs. 100,000 takes to double at 8% a year compounded yearly.Unit IIn a survey of 120 customers, 70 buy tea, 55 coffee and 25 both. Draw a Venn diagram and find how many buy neither.Unit IIExpand (x − 2)⁵ by the binomial theorem.Unit IIFind the sum to infinity of 12 + 6 + 3 + … and the sum of its first 6 terms.Unit IIFind the amount of Rs. 200,000 at 10% a year compounded half-yearly for 3 years.Unit IIIFind the present value of Rs. 500,000 due in 4 years at 10% compounded yearly.Unit IIIFind the yearly deposit into a sinking fund to reach Rs. 5,000,000 in 5 years at 10%.Unit IIIDemand is Qd = 1,000 − 4p and supply Qs = 6p − 200. Find the equilibrium price and quantity.Unit IVCost is Rs. 16,000 for 100 cards and Rs. 22,000 for 250 cards. Find the linear cost function and the cost of 400 cards.Unit IVDemand is p = 80 − q. Find the revenue function and the maximum revenue.Unit IVFind and classify the stationary points of y = x³ − 3x² − 9x + 5.Unit VA shop sells 2,000 units a year; each order costs Rs. 400 and holding costs Rs. 10 a unit a year. Find the economic order quantity.Unit VDemand is p = 120 − 2q and supply p = 20 + 0.5q. Find the consumer and producer surplus at equilibrium.Unit VFor A = [2 5; 1 3] and B = [4 0; −2 6], find AB and BA and comment.Unit VISolve x + 2y = 8 and 3x − y = 3 by row reduction.Unit VIFind the inverse of [4 7; 2 6] and use it to solve 4x + 7y = 220, 2x + 6y = 160.Unit VI
Long problems
A firm's profit (Rs. '000) is P = −x² + 120x − 2,000. Find the break-even outputs, the profitable range, and the profit at 60 units.Unit IA factory must make 500 garments using exactly 18,000 machine minutes; a shirt takes 30 minutes and trousers 45. Form and solve equations for the plan.Unit IExplain the real number system with a diagram, and find the HCF and LCM of 84 and 90 by prime factors.Unit IA clerk's salary starts at Rs. 60,000 a month with a Rs. 2,500 yearly increment. Find the year-10 salary, the 10-year total, and the first year above Rs. 85,000.Unit IISales of Rs. 400,000 grow 10% a year. Find year-5 sales and the 5-year total, and compare with a fixed Rs. 40,000 yearly rise.Unit IIA committee of 5 is chosen from 6 men and 5 women. Find the number of committees with exactly 2 women and with at least 1 woman.Unit IIA Rs. 331,000 loan at 10% is repaid in 3 equal year-end instalments. Find the instalment, prepare the schedule and find the total interest.Unit IIIA Rs. 2,000,000 renovation returns Rs. 800,000, Rs. 900,000 and Rs. 1,000,000 over 3 years. Find the NPV at 12% and advise.Unit IIIGoods listed at Rs. 150,000 carry trade discounts of 20% and 10% and terms 2/10, n/30. Find the net price, the day-8 payment and whether borrowing at 12% to take the discount pays.Unit IIIA bakery: price Rs. 1,500, variable cost Rs. 900, fixed cost Rs. 360,000. Find the break-even point, profit at 800 cakes, the units for a Rs. 150,000 profit and the margin of safety; draw the chart.Unit IVDemand p = 600 − 2q, cost C = 100q + 20,000. Without calculus, find the maximum profit, its price and the break-even outputs.Unit IVDemand p = 200 − 3q, supply p = 40 + 5q. Find the equilibrium, then the effect of a Rs. 16 per-unit tax on sellers.Unit IVR(x) = 150x − 0.2x², C(x) = 2,000 + 40x + 0.05x². Find the profit-maximising output, price and profit, and show that MR = MC.Unit VFor C(x) = 2,000 + 40x + 0.05x² and R(x) = 150x − 0.2x², find MC and MR at 200 units, interpret, and find the profit there.Unit VMC = 30 + 0.6x and fixed cost Rs. 8,000. Find the total cost function, the cost of 100 units and the extra cost of increasing output from 100 to 200 units.Unit VSolve x + y + z = 6, 2x − y + z = 3, x + 2y − z = 2 by Gauss-Jordan elimination.Unit VIFind the inverse of [1 2 3; 0 1 4; 5 6 0] by the cofactor method and use it to solve AX = [14; 14; 17].Unit VITwo branches sell three goods. Use a quantity matrix and a price matrix to find each branch's revenue and the total.Unit VI

Answer frames

How to lay out a long answer, with a write-up check. 26 frames so far.

STRUCTURED-ANSWER FRAME · UNIT IExplain the real number system with examples, and find the HCF and LCM of 84 and 90.STRUCTURED-ANSWER FRAME · UNIT IFactorise fully: (a) 3x² − 12 (b) 6x² − x − 2. Show your checks.STRUCTURED-ANSWER FRAME · UNIT ISimplify (2x³y²)³ ÷ (4x⁵y), then solve 3^(2x−1) = 27.ESSAY FRAME · UNIT IA garment factory makes shirts and trousers. It must make 500 garments in total, using exactly 18,000 machine minutes. A shirt takes 30 minutes and a pair of trousers 45 minutes. How many of each should it make?ESSAY FRAME · UNIT IA firm's monthly profit (Rs. '000) is P = −x² + 120x − 2,000. (a) Find the break-even outputs. (b) State the profitable range. (c) Find P at x = 60.ESSAY FRAME · UNIT IIOf 200 students, 90 study Accounting, 80 Economics and 70 Maths; 30 take Accounting and Economics, 25 Accounting and Maths, 20 Economics and Maths, and 10 all three. Draw a Venn diagram and find how many take (a) at least one, (b) none, (c) Accounting only.ESSAY FRAME · UNIT IIA committee of 5 is to be chosen from 6 men and 5 women. In how many ways if (a) it has exactly 2 women, (b) it has at least 1 woman? (c) How many arrangements of COLOMBO are there?STRUCTURED-ANSWER FRAME · UNIT IIExpand (2x − 1)⁴ using Pascal's triangle, and find the coefficient of x³ in (x − 2)⁵.ESSAY FRAME · UNIT IIA clerk starts on Rs. 60,000 a month with a Rs. 2,500 increment each year. Find (a) the monthly salary in year 10, (b) the total earned in 10 years, (c) the first year in which the monthly salary exceeds Rs. 85,000.ESSAY FRAME · UNIT IIA bakery's sales are Rs. 400,000 in year 1 and grow 10% a year. (a) Find sales in year 5. (b) Find total sales over 5 years. (c) Compare with sales that grow by Rs. 40,000 a year instead.ESSAY FRAME · UNIT IIIA retailer buys goods listed at Rs. 150,000 with trade discounts of 20% and 10%, on terms 2/10, n/30. (a) Find the net invoice price. (b) Find the amount paid on day 8. (c) Find the single equivalent discount. (d) Is it worth borrowing at 12% simple interest for 20 days to take the cash discount?ESSAY FRAME · UNIT IIIRs. 100,000 is invested for 2 years at 12% a year. Find the amount under (a) simple interest, (b) yearly, (c) quarterly and (d) monthly compounding. Comment on the results.ESSAY FRAME · UNIT IIIA hotel can spend Rs. 2,000,000 on a renovation returning Rs. 800,000, Rs. 900,000 and Rs. 1,000,000 at the end of years 1-3. Using a 12% required rate, find the NPV and advise management.ESSAY FRAME · UNIT IIIA Rs. 331,000 loan at 10% a year is repaid by 3 equal instalments at the end of each year. (a) Find the instalment. (b) Prepare the repayment schedule. (c) Find the total interest.STRUCTURED-ANSWER FRAME · UNIT IVGiven f(x) = 4x − 8: (a) find f(3); (b) state the domain and range; (c) find f⁻¹(x) and check your answer.STRUCTURED-ANSWER FRAME · UNIT IVA printing shop's cost is Rs. 16,000 for 100 cards and Rs. 22,000 for 250 cards. Find the linear cost function, explain the slope and intercept, and find the cost of 400 cards.ESSAY FRAME · UNIT IVA bakery sells cakes at Rs. 1,500. Variable cost is Rs. 900 a cake and fixed cost Rs. 360,000 a month. (a) Write C(x), R(x) and P(x). (b) Find the break-even point in cakes and rupees. (c) Find the profit on 800 cakes. (d) How many cakes give a profit of Rs. 150,000? (e) Find the margin of safety at 800 cakes.ESSAY FRAME · UNIT IVDemand for a vegetable is p = 200 − 3q and supply is p = 40 + 5q (p in Rs. per kg, q in '000 kg). (a) Find the equilibrium. (b) A tax of Rs. 16 per kg is placed on sellers. Find the new equilibrium, the share of the tax paid by buyers and sellers, and the tax revenue.ESSAY FRAME · UNIT IVA firm's demand is p = 600 − 2q and its cost is C = 100q + 20,000. Without calculus: (a) find the revenue and profit functions; (b) find the output and price that maximise profit, and the maximum profit; (c) find the break-even outputs; (d) sketch the profit curve.STRUCTURED-ANSWER FRAME · UNIT VEvaluate (a) lim (x → 3) (x² − 9)/(x − 3); (b) lim (x → ∞) (4x² + 3x)/(2x² − 5); (c) explain what happens to AC = 20 + 5,000/x as x → ∞.ESSAY FRAME · UNIT VA firm's cost is C(x) = 2,000 + 40x + 0.05x² and its revenue R(x) = 150x − 0.2x². (a) Find MC and MR. (b) Evaluate them at x = 200 and interpret. (c) Find the profit at x = 200 and the marginal profit.ESSAY FRAME · UNIT VA firm has R(x) = 150x − 0.2x² and C(x) = 2,000 + 40x + 0.05x². Find the output that maximises profit, prove it is a maximum, and find the maximum profit and the price.ESSAY FRAME · UNIT VA factory's marginal cost is MC = 30 + 0.6x and its fixed cost is Rs. 8,000. (a) Find the total cost function. (b) Find the cost of 100 units. (c) Find the extra cost of raising output from 100 to 200 units. (d) Demand is p = 120 − 2q and the market price is Rs. 40: find the consumer surplus.STRUCTURED-ANSWER FRAME · UNIT VITwo branches sold: Branch 1: 20 tea, 15 sugar, 30 rice; Branch 2: 25, 10, 40. Prices: Rs. 450, Rs. 280, Rs. 320. Use matrices to find each branch's revenue and the total.ESSAY FRAME · UNIT VISolve by Gauss-Jordan elimination: x + y + z = 6, 2x − y + z = 3, x + 2y − z = 2.ESSAY FRAME · UNIT VIGiven A = [1 2 3; 0 1 4; 5 6 0], find A⁻¹ by the cofactor method and use it to solve x + 2y + 3z = 14, y + 4z = 14, 5x + 6y = 17.