新紀元數學 1a 答案(20)

12
Shirley's profit per cent=(280-200)/200 x100%=45%
William's profit per cent=(87-60)/60 x100%=40%
William's profit per cent is greater.
13
(15x16-200)/200 x100%=20%
14
Kelvin's loss per cent=(350-280)/350 x 100%=20%
Jenny's loss per cent=(450-369)/450 x 100%=18%
Jenny's loss per cent is smaller.
15
(480-3.5x12x10)/480 x100%=12.5%
16(a)
(a)200000 x 7/8=175000
(b) (200000-175000)/200000 x100% =12.5%
17
Let the cost price of each toy car is $x.
x(40%)=2800000/20000
x=350
18
6除(1+20%) x (1+10%)=$5.5
19
Let the profit per cent is x.
profit=230除(1+15%)=200
The profit per cent if it was sold at $250:
(250-200)/200 x100%=25%
20
(2700+300)x(1+20%)=$3600
21(a)
Let the profit per cent is x.
profit=7760除(1-3%)=$8000
The loss per cent if it was sold at $7440:
(8000-7440)/8000 x100%=7.5%
(b)
8000x(1+10%)=$8800
22
{[500 x (1-30%) +750 x (1+24%) -(500+750)] / (500+750)} x100%
=2.4%