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The question is "it is given that the world population in 2005 was 6.47 x 10^9, and 1.49 x 10^8 km^2 of the area of the Warth is land. Suppose people on the Earth live on 10% of the land, find the average population density(poplulation/km^2)of the world"

全球陸地共有1.49 x 10^8 km^2
其中只有10%的有人居住,,所以係1.49 x 10^8 *10%=1.49 x 10^7 km^2
所以,平均每km^2有(6.47 10^9)/(1.49 x 10^7)人住
即係434.2281879=>434 population/km^2

thx

It is given that the world population in 2005 was 6.47 x 10^9, and 1.49 x 10^8 km^2 of the area of the Earth is land. Suppose people on the Earth live on 10% of the land, find the average population density (poplulation/km^2) of the world.(Give your answer correct to 3 s.f.)

首先搵左10% of the land (住人既地土面積)
(1.49x10^8) x 10%=14900000=1.49x10^7
then the average population density
=(world population) / (10% of the land)
=(6.47 x 10^9) / (1.49x10^7)
=434.228188
=434 poplulation/km^2 (cor to 3 s.f.)

2007-04-25 19:44:57 補充：
補充the average population density因為你要搵poplulation/km^2重點係per km^2所以要(world population) / (10% of the land)