f1 maths=] help plzT_T

[匿名]

2010-02-01 12:53 am

1)Albert and Betty play a game of guessing numbers.

a)Albert asks Betty to guess two numbers whose profuct is -300 and quotient is
-12.Betty replies that they are -60 and 5,but Albert thinks that there is another possible set of numbers for the answer.Find the possible set.

b)Betty asks Albert to guess two numbers whoose product is 180 and quotient is
-20.Albert replies that this is not possible.Do you agree with Albert?
Give reasons.

2)A man borrows $50 000 from a finance company at 12% p.a. simple interest.
He useall the money borrowed to buy some watches at $200each.Then he sells
the watches each at a profit of 32.5%.After half a year, he returns the total
amount borrowed together with the interest charged to the finance company.

a)If he sells all the watches,what is his overall profit in that half year?

b)Find the least number of watches he must sell in that half year in order not to
lose money.

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回答 (1)

用戶2053

2010-02-01 4:07 am

✔ 最佳答案

1a)Let two numbers be A , B :
AB = -300.....(1)
A/B = - 12.....(2)
(1)*(2) :
AAB/B = -300 x (-12)
A^2 = 3600
A = 60 or - 60
B = - 5 or 5
Hence the other possible set is 60 , - 5
1b)Agree.
AB = 180......(1)
A/B = -20......(2)
(1)*(2) :
A^2 = - 3600
A have no real solutions.

2a) He bought 50 000/200 = 250 watches
If he sells all the watches , he will earn 250 * 200*32.5% = $16250
overall profit = 16250 - half-year interest charged
= 16250 - 50 000*12%*(1/2)
=$13250
b) Let the least number be x (integer):
he will earn x * 200*32.5% = 65x
65x >= half-year interest charged
65x >= 50 000*12%*(1/2)
x > = 46.15...
x = 47
He must sell 47 watches in that half year in order not to lose money.

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