### Box-and-whisker plots

Box-and-whisker plots A box-and-whicker plot is a diagram that shows the distribution of a set of data at a glance. They are drawn using five summary statistics: the lowest and highest values( the range), the first and third quartiles (The interquartile range) and the median. Drawing box-and-whisker plots All box-and-whisker plots have the same basic […]

### Calculating averages and ranges for grouped continuous data

Calculating averages and ranges for grouped continuous data Some data is discrete and can only take on certain values. For example, if you throw an ordinary die then you can get one of the numbers 1,2,3,4,5 or 6. If you count the number of red cars in a car park then the result can only […]

### Making comparisons using averages and ranges

Making comparisons using averages and ranges Having found a value to represent you data (an average) you can now compare two or more sets of data. However, just comparing the averages can sometimes be misleading. It can be helpful to know how consistent the data is and you for this by thinking about how spread […]

### Different types of averages

Different types of averages An average is a single value used to represent a set of data. There are types of average used in statistics and the following shows how each can be calculated. Tip! There is more than one “average” so you should never refer to the average.Always specify which average you are talking about: […]

### Percentiles and quartiles

Percentiles and Quartiles Johns accountancy firm is advertising for new staff to join the company and has set an entrance test to examine the ability of candidates to answer question on statistics. In a statement on the application form the company states that. All those candidates above the 80th percentile will be offered an interview. What […]

### Probability

Probability Basic ProbabilityWhen you roll a die you may be interested in throwing a prime number. When you draw a name out of a hat, you may want to draw a boys name. Throwing a prime number or drawing a boys name are examples of events. Probability is a measure of how likely an event is to […]

### Possibility diagrams

Possibility diagrams The probability space is the set of all possible outcomes. It can sometimes simplify our work if you draw a possibility diagram to show all outcomes clearly. See how drawing a possibility diagram helps solve problems in the following example. Example 1: Two dice, one red and one blue, are thrown at the same time and […]

### Using charts to display data

Using charts to display data Charts are useful for displaying data because you can see patterns and trends easily and quickly. You can also compare different sets of data easily. In this section you are going to revise what you already know about how to draw and make sense of pictograms, bar chats and pie […]

### Percentage

Percentage A percentage is a fractions with a denominator of 100. The symbol used to represent percent is %. To find 40% of 25, you simply need to find $displaystyle frac{{40}}{{100}}$ of 25. Using what you know about multiplying fractions: $displaystyle frac{{40}}{{100}}times 25=frac{{cancel{{40}}}}{{cancel{{100}}}}times frac{{25}}{1}=$ $displaystyle frac{2}{{cancel{5}}}times frac{{cancel{{25}}}}{1}=frac{2}{1}times frac{5}{1}=10$ So, 40% of 25 = 10 Equivalent forms […]