又係S.1 Maths (超急，聽日考!)

A company purchased 50 sets of software at $80 000.The first 40 sets were sold at $2000 each and the remaining 10 sets were sold at $900 each.
a)
The cost of each set of software
= $ 80 000 / 50
= $1 600
Profit per cent
= [($2000 - $1600)/$1600] x 100%
= ($400/$1600) x 100%
= 25%

b)
Loss per cent
= [($1600 - $900)/$1600] x 100%
= ($700/$1600) x 100%
= 43.75%

c)
Amount of money earned from selling the 50 sets of software
= $2 000 x 40 + $900 x 10
= $80 000 + $9 000
= $89 000
Since the amount of money earned from selling the 50 sets of software > the total cost of the 50 sets of software,
Profit per cent
= [($89 000 - $80 000)/$80 000] x 100%
= ($9000 / $80000) x 100%
= 11.25%
Therefore, the profit per cent is 11.25%.

If there is any mistake, please inform me.

c)
Amount of money earned from selling the 50 sets of software
= $2 000 x 40 + $900 x 10
= $80 000 + $9 000
= $89 000
Since the amount of money earned from selling the 50 sets of software > the total cost of the 50 sets of software,
Profit per cent
= [($89 000 - $80 000)/$80 000] x 100%
= ($9000 / $80000) x 100%
= 11.25%
Therefore, the profit per cent is 11.25%.

(40*2000+10*900)-80000
---------------------------- *100%
80000

=9000
---------- *100%
80000

=11.25%

2008-01-15 15:07:57 補充：
so the profit percent is 11.25%