Demographic math

1
Demographic math

• Two things you will be able to do at the end of
  this lesson
• Calculate a populations doubling time
• Predict future population size
• Please get out a calculator

2
Doubling time

• Formula Time 70 r
• r growth rate
• Example a country is growing at 2 a year. In
  how many years will the countys population
  double?

3
Practice

• The Ivory Coast is growing at 3.8 each year. In
  how many years will it double?
• China is growing at 1.2. In what year will
  Chinas population be double what it is today?

4
Calculating future population size

• A Pert
• A future population size
• P current population size
• Constant e 2.72
• Growth rate r reported as percent of percent
• T time

5
A Pert

• Try one!
• The US population this year is 306 million and
  our growth rate is .6. How large will the
  population be in 2050?

6
Try another one! ?

• The worlds population is about 7.058 billion and
  our growth rate is 1.2. Assuming the rate stays
  constant, how big will the population be by 2050?
  By 2100?

7
Check for understanding

• What two calculations did you just learn how to
  do?
• What can you use A Pert for?
• Which equation is simpler?
• What is the common mistake that is made in the A
  Pert formula?

8
Check your answers!

• 1. 405.5 million
• 2. 1.28 billion
• 3. 8.5 billion
• 4. More developed 700 years Less developed
  41 years

9
Back side!

• China
• 1999 70 years 1.83 billion
• 2000 77.7 years 1.88 billion
• 2014 140 years 1.6 billion

10

• India
• 1999 36.8 years 2.59 billion
• 2000 - 38.8 years 2.45 billion
• 2014 46.6 years 2.21 billion