F.3 maths quesion - Area and Volume

用戶95851

2007-04-07 3:22 am

請列明步驟及解釋!!
It is known that nearly 70% of the surface of the Earth are oceans.
a) The radius of the Earth is 6400km. Find the total area of the oceans on the Earth.
b) Miss Chan, a geography teacher, uses a globe of scale 1:40 000 000.
　i) What is the total area of the oceans (in cm^2) on the globe?
　ii) If the area of China on the globe is 60cm^2, find the actual area (in km^2) of China.

from: exploring mathematics 3B Supp Ex.11 P.219 #21
PS... 有誰是F.3 學生可解答我的問題?

回答 (1)

myisland8132

2007-04-07 3:57 am

✔ 最佳答案

我不是F.3 學生﹐不過我試0下答啦

(a)
the total area of the oceans on the Earth.
=4π(6400)^2(70%)
=360302978.301952 km^2

(b)
i)
in the globe
1 cm represents 40 000 000 cm=4*10^7 cm
1 cm^2 represents 16*10^14 cm^2=1.6*10^15 cm^2=1.6*10^11 m^2=1.6*10^5 km^2
the total area of the oceans (in cm^2) on the globe
=4π(6400)^2(70%)/(1.6*10^5)
=2251.8936 cm^2
(ii)
the actual area (in km^2) of China.
=60*1.6*10^5
=9600000 km^2

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