Human Population Math

Population Density # of indiv. of a species unit of area A better way to describe the size of a population ex. 270,000,000 people = 29 people/Km 2 in the US 9,166,605 Km 2

Birth and Death Rate b = birth _ or Births per thousand Total population1000 d = death or Deaths per thousand Total population1000 ex. b = 23, 452/942,721 = x 100= 2.5% Same as 25/1000 = x 100= 2.5%

What Causes Populations to Change in Size? Rate of change ( r ) = Four ways to find r: When using r, identify your variables and then pick the equation that fits!

Rate of change ( r ) = 1. Total births - total deaths/ total population r = 23, , 228 = x 100=.66% r = 23, , 228 = x 100=.66% 942, , birth rate (b) -death rate (d) r = = x 100=0.7% r = = x 100=0.7%

Rate of change ( r ) = (Total births + total immigration) - (total deaths + total emigration) / total population r = (23, )-(17, ) = 942,721 = x 100 = 1.4% 4. (birth rate (b) + immigration rate(i)) - (death rate (d) + emigration rate (e) ) x 100 r = ( ) - (18 + 3) = x 100 = 1.4%

Doubling Time

Time to take for a population with a stable growth rate to double in size Doubling Time ( t d ) = t d = 70% or.7 r r Ex. Brazil will double its population in how many years with the present growth rate of 1.7%? A:.7/0.017 or 70%/1.7% = 41.2 years

Maximum Population Growth (MPG) Influenced by Biotic Potential – – different for each species – – can change with conditions MPG is always exponential under ideal conditions

You figure out the growth Rate of a Pop: Remember: r = (b - d ) + (i - e ) b =.01 d =.005 i =.001e =.01 So now: Calculate growth rate and Calculate doubling time

Determining future Pops: Remember: N (t) = N 0 e rt N(t) = population after t years N 0 = initial population size r = growth rate t = time

You Determine the future Pop of Duttania: Remember: N (t) = N 0 e rt The island of Duttania has 435 people. Their growth rate is 2%. What will be the population after 10 years? A: 531 people.