5.1 Experimental probability

Several people can play this game (or a whole class can play). Every person chooses a number to represent their horse. They each take it in turns to roll two dice and sum their numbers and when their number comes up they shade one box for their horse.

So if someone gets a 2 and a 3, their total is 5 and they shade one square on the 5 line. The race is won by the first horse to get to the finishing line (that is when all five boxes on their line are shaded).

When the game is finished you should have a horizontal bar chart.

Figure 33 Horse race

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A table and bar chart showing the frequencies of each “horse” from 1 to 12, showing data collected during a two dice horse race. The values for 1 to 12 respectively are: 1, 6, 11, 7, 12, 9, 20, 6, 12, 7, 5, 5. The bar chart has a bar for each horse from 1 to 12 and the heights of the bars match the frequencies in the table.

Figure 33 Horse race

If you do not have any dice, there are simulators available online, for instance:

www.random.org/ dice/ ?num=2 [Tip: hold Ctrl and click a link to open it in a new tab. (Hide tip)]

www.transum.org/ software/ SW/ SnailRace/

Some questions to get you thinking about the activity.

• How did your horse do?
• Did anything surprise you about the results you recorded?
• Was the winning horse one you might have expected to win?
• Did you notice anything about horse number 1?

You will calculate the theoretical probabilities of each horse moving forward in the race later, in Section 5.3.