s1 math per cent 難題 x4

2012-01-01 7:39 am

1.A shop sold a portable computer at a discount of 5%.The discount is $350.

1a)What is the marked price of the portable computer?

2b)If the profit per cent is 33%,find the cost of the portable computer.

2.David deposits $2000 in a bank at simple interest. 3 years later,he obtain an amount of $2240.find the interest rate per annum?

3.Helen borrows $3000 from a bank at an interest rate of 24% p.a. for 18 months.

3a)Find the interest she has to pay.

3b) If she uses method of monthly instalment to pay the debt,what to pay the dabt,what is her monthly payment?

4)A furniture shop sells a set of table with 4 chairs,In this season,the cost of the table and chairs increased.

Original cost % increase
Table $600 20%
Chair $100 15%

The owner of the shop claims that the cost of the set of table with 4 chairs is increased by 18%. Is the claim reasonable? Explain tour answer.

回答 (1)

myisland8132

2012-01-01 7:58 am

✔ 最佳答案

1(a) Let the marked price is x

x * 5% = 350

x = 7000

(b) Let the cost is C

(7000 - C)/C = 33%

1.33C = 7000

C = 5263.15789

2 2000 + 2000 * R * 3 = 2240

6000 * R = 240

R = 0.04

The interest rate is 4%

3(a) Interest = 3000 * 24% * 18/12 = 1080

(b) Her monthly payment

= (3000 + 1080)/18

= 226.6667

4 Original cost = 600 + 100 * 4 = 1000

New cost = 600 * (1 + 20%) + 100 * 4 * (1 + 15%)

= 1180

% increase = (1180 - 1000)/1000 = 180/1000 = 18%

So, the claim is reasonable.

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