This task is about comparing theoretical with experimental outcomes.
Practical Task
Throw the three coins together. Score a "head" as 1 point and a "tail" as 2 points.
a)  i)  Add the three scores together, repeat this a total of 80 times and record your results in the tally chart below.  


ii)

Complete the table below using the information from the tally chart above.




b)

There are eight ways that the coins can come up. They are:




The probability of getting the three coins summing to 3 (i.e., three heads) is ^{1}⁄_{8}.
Complete the table of probabilities. The first one has been done for you.


c)

Use the table above to predict how many times you would expect to get each of the following sums if the three coins were thrown 80 times.


i)
ii)
iii)
iv)

A sum of 3? __________
A sum of 4? __________
A sum of 5? __________
A sum of 6? __________



d) 
Write a statement comparing the expected frequencies in c) with what you actually got in the experiment in part a) ii).


e)

Why may the results in a) ii) and c) be different?
Give two reasons.


