# Line Graphs

**Line Graphs** show **continuous data**. Examples include the world population, the value of the dollar, average daily temperatures, a patient's temperatures, and distances travelled on a journey.

Of the two variables in bar graphs, the **independent variable** is the one on which the other variable depends. The independent variable goes on the horizontal axis and a common example is the months of the year.

The **dependent variable** is written on the vertical axis and a common example includes the frequency.

**Some important tips are:**

- The numbers that are used on the axes should go up by 1s, 2s, 5s, 10s, 20s, 50s, 100s, 200s, 500s, 1000s and so on.
- Never use other numbers such as 3s, 4s, 6s, 7s, 8s and 9s.
- The axes do not have to start at zero.

## Example - Computing Power

Moore's Law of Computing Power states that the number of components in integrated circuits (associated with processing speed, memory capacity, and the number of pixels in cameras) doubles every 2 years.

YEAR (INDEPENDENT VARIABLE) | CAPACITY (DEPENDENT VARIABLE) |

2010 | 1 000 gigabytes |

2012 | 2 000 gigabytes |

2014 | 4 000 gigabytes |

2016 | 8 000 gigabytes |

2018 | 16 000 gigabytes |

2020 | 32 000 gigabytes |

**Answer:**

## Did You Know That...?

The world population in 2011 passed the 7 billion mark. That's you, me and 6 999 999 998 other humans - all breathing the same air and needing the same nutrients on our planet with its finite resources.

YEAR (INDEPENDENT VARIABLE) | WORLD POPULATION (DEPENDENT VARIABLE) |

2000 | 6.115 billion |

2010 | 6.909 billion |

2020 | 7.675 billion |

2030 | 8.309 billion |

2040 | 8.807 billion |

2050 | 9.150 billion |

## Question

Draw a line graph of the world population using the estimated data in the table above. Extend that table till the year that you believe you will be a grandparent. How many others will be on Planet Earth then?