中一maths

1. 長方體水缸內水的總體積
=1 * 0.8 * 0.6 *1/2
=0.24m^3
器皿的底面積
=0.24m^3 / 24
=0.01m^2
=100cm^2
2. 750個邊長是12cm的正方體積木的總體積
=12 * 12 *12 * 750
=1296000cm^3
=129.6m^2
木箱的高度
=129.6 / 1.8 / 0.6
=120m

question 1 :

ans 1)
let x cm^2 be the area .

24cm * x cm^2 = 1*100cm * 0.8*100cm * 0.6*100cm * 1/2

--> xcm^2 = 50cm*80cm*60cm / 24cm

-->x cm^2 = 10000 cm^2

ans 2)

let y m^2 be the area.

0.24m * ym^2 = 1m*0.8m*0.6m*1/2

--> ym^2 = 0.5m*0.8m*0.6m / 0.24m
--> ym^2=1m^2

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question 2:

let y m be the high.

1.8m* 0.6m*ym =750* 0.12m*0.12m*0.12m

--> 1.08m^2 *ym =1.296m^3

--> ym = 1.296m^3 / 1.08m^2

-->y m = 1.2m