Population problem

mcwang719

Junior Member
Joined
Mar 22, 2006
Messages
67
Hello.
The question is: The land area in the world is about 1.5x10^6 km^2. Using present world population growth rates determine how many years will elapse before one person will have only 1m^2 of land ("standing room only").
growth rate = 1.68 world population (1995)= 5,759 million.
the answer in the back of the book is 610 years from 1995.

Ok so this is what i'm doing: I use the equation N/No=e^(lambda)(t). I convert 1.5x10^6 km^2 to 1.5x10^11 m^2 so I use current world population for No=5.759x10^9 and N= 1.5x10^11 and lambda = .0168 then solve for t(time). My answer is nothing like 610 yrs. Any help would be greatly appreciated. thanks!
 
Give N0 another try. km^2 = (1000 m)^2 = 1000000 m^2
 
i don't understand for No i use the world population 5,759,000,000 = 5.759x10^9.
Actually i made a mistake N= 1.5x10^12. But I still get an incorrect answer.
 
mcwang719 said:
The question is: The land area in the world is about 1.5x10^6 km^2.
Should be 1.5x10^8 km^2 ; typo? (that's 150,000,000,000 m^2)

5759000(1.0168)^610 = ~149,288,028,000 ; looking good!
 
yeah you're right. i did some research and the area of the world is 1.5x10^8 km^2. So it must be a typo. These typos can drive a person crazy!! thanks for your help!!
 
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