Population Growth
Maths: Edexcel A Level Pure Maths, topic 6.2.1
Growth
Growth can be thought of as when something gets larger over time. This might be the population of a particular species, the amount of money in a bank account or the number of people using Seneca.
Linear growth
- Linear growth is when something increases by a steady amount over set time periods.
- E.g. a cinema gets 100 extra visitors each month.
- If they have 200 visitors in month 1, they will get 300 visitors in month 2, 400 visitors in month 3, 500 visitors in month 4, etc.
Exponential growth
- Exponential growth is when something increases by a multiplier (or percentage) over set time periods.
- E.g. the number of people playing Fortnite increases by 2× each month.
- If they have 200 users in month 1, they will get 400 users in month 2, 800 users in month 3, 1,600 users in month 4, etc.
Exponential growth in bacteria
- Populations of bacteria can grow exponentially.
- This means the number of bacteria increases by a set multiplier over a given time period.
Exponential growth in bacteria 2
- The population of an example colony of bacteria starts at one.
- If the population of bacteria doubles every hour you'd get the exponential growth seen above.
Test yourself on Population Growth
The amount of time I spend on my phone increases by 10 minutes a day. I spend 2.5 hours on my phone on Monday. How long did I spend on my phone on Friday of the same week?
The population of a colony of bacteria doubles every week. If the colony starts with 6 bacteria, how many bacteria will there be after 15 weeks?