1)A camera which costs $3600 is sold at a profit of 5% . Find the selling price .
2)John invests $24000 in a bank at a rate of 4% p.a. simple interest . How long does it take for him to receive an amount of $28800?
3)Becky bought an umbrella at a 30% discount . If she paid $119 , find the marked price of the umbrella .
4)Queenie' s height is 10% more than Robert . Peter' s height is 20% less than Queenie . Queenie is 165cm tall . Who , Peter or Robert , is taller ? Explain your answer ,
5)Chris has a book and its marked price is $240 . He then sells it to Susan at 15% discount . If he can make 20% profit , find the cost of the book .
Math文字題
2012-11-11 7:10 am
回答 (2)
2012-11-11 5:37 pm
✔ 最佳答案
1) Cost = $3600
Profit = 4% of cost = $3600 x 0.05 = $180
Selling price = cost + profit = $3600 + $180 = $3780
Selling price = $3780 (answer)
2)
Total Interest = $28800? - Principal = $28800 - $24000 = $4800
Total interest = Principal x interest rate per annum x number of years
$4800 = $24000 x 0.04 x number of years
Number of years = $4800/($24000 x 0.04) = 5
It takes 5 years. (answer)
Note: $28800 includes principal and interest. John receives both principal and interest after 5 years.
3)
Selling price = Marked price – Discount = marked price – marked price * discount in %
$119 = MP – MP x 0.3
$119 = MP(1 – 0.3)
MP = $119/0.7 = $170
Marked price = $170 (answer)
Note: MP = marked price
4)
Queenie height = 165 cm
Robert’s height x 110% = Queenie height = 165 cm
Robert’s height = 165 cm/110% = 165 cm/1.1 = 150 cm
Peter’s height = 165 cm x (100% - 20%) = 165 cm x 0.8 = 132 cm
Robert is taller than Peter because 150 cm (Robert’s height) is longer than 132 cm (Peter’s height) ~ (Answer)
5)
Marked price = $240
Discount = Marked price x discount rate = $240 x 15% = $240 x 0.15 = $36
Selling price = marked price – discount = $240 - $36 = $204
Profit % = (Selling price – cost)/cost x 100%
20/100 = Selling price – cost)/cost
0.2 = ($204 – cost)/cost
0.2 x cost = $204 – cost
1.2 x cost = $204
cost = $204/1.2 = $170
The cost of the book is $170 (answer)
Comment:
I try to do your questions in great details, so that you can follow each step.
Also the answer should include appropriate unit.
2012-11-11 9:28 am
1)
3600*1.05 = 3780
2)
24000(0.04)n=28800
n=30 years
3)
119/0.7 = 170
4)
Queenie is 165cm tall
Peter is (165*0.8)=132cm tall
Robert is 165/1.1=150cm tall
So Peter is taller
5)
Cost = 240*0.85/1.2=170
3600*1.05 = 3780
2)
24000(0.04)n=28800
n=30 years
3)
119/0.7 = 170
4)
Queenie is 165cm tall
Peter is (165*0.8)=132cm tall
Robert is 165/1.1=150cm tall
So Peter is taller
5)
Cost = 240*0.85/1.2=170
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