F.1 數學(英文) 2

(1) I wonder if the whole question is copied here as it seems not enough information provided in the question, i.e. total sum of money / Jack and Jane share the sum of money equally at first?

So i assume they equally share the money at first.

Let X be the original share of Jane,

X(1+15%)=1380
X=1200

Therefore, Jack now got (1380-1200)=$180 less

% Decrease in share
= decrease in share / original share
=180/1200
=15%

(2a) Let X be the cost of machine he makes a profit,

X(1+10%)=19800
X=19800 / (1+10%)
X=18000

Let Y be the cost of machine he suffers a loss,

Y(1-10%)=19800
Y=19800 / (1-10%)
Y=22000

Total sales - Total cost
= ($19800 x 2) - ($18000 + $22000)
= $39600 - $40000
= -$400 (which mean a loss)

(2b) Loss % = loss / total cost
=400/40000
=1%

2007-01-02 11:42:48 補充：
remember, in question (2)the man sell the machine at $19800$19800 is the selling price, not the cost, don't mix it!!therefore, we should at first find out the cost of machine and then compare with the selling price ($19800) in order to calculate the profit / loss

2007-01-02 11:46:42 補充：
not base on the selling price to calculate like: 19800 x (1 10%) or 19800 x (1-10%)

1.
jane's original share:
1380 / (1 + 0.15) = 1200

percentage change of jack's share:
[(1200 - 180 - 1200) / 1200] x 100%
= -15% (decreased)


2.a)
19800 x 2 - 19800 x (1 + 0.1) - 19800 x (1 - 0.1)
= 19800 x (2 - 1.1 - 0.9)
= 0

b)
as there is no profit or loss
the percentage change is also 0% on the whole

Z x 1+15% = 1380
Z x 115%除115%=1380 除115%
Z = 1200 = Jane 本來
15%=180 = Jack 比左幾多
1. -15% (因為jack少左)

2. 19800 X90% + 19800X 110%
2A2B都係0,因為一個110%,一個90%加起係200%,2個machine=200%除2=100%
會抵銷左,即係冇上冇洛