1. What is the difference between a histogram and a bar (column) graph?
Histograms are used for continuous data such as frequencies of people of a range of heights or weights.
Bar graphs are used for discrete data such as the frequencies of the number of cars of a certain colour.
2. Should straight lines or a curve be used to join the points on a cumulative frequency graph?
Straight lines are normally used although a smooth curve is also acceptable.
3. What happens on a histogram if one of the intervals is a different width to the rest?
If an interval is, say, twice as long as another, then its frequency, or the height of the bar, must be halved.