Biomedical Engineering Reference
In-Depth Information
H or T uppermost, and so the theoretical probability of either event is
1
/
2
. Table 7.7 shows
a typical result.
Table 7.7
Heads and tails
Experiment
1
2
3
4
5
6
7
8
9
10
Outcome
T
T
T
H
H
T
H
T
T
T
If I plot out the results (Figure 7.6) we see that the result is of course unpredictable. We
cannot say what each result will be.
Ten throws of coin
1
0.5
S1
0
1
2
3
4
5
6
7
8
9
10
Throw
Figure 7.6
Single coin tossed 10 times
I now increase the number of coins to 10 and repeat the experiment again 10 times. That
is to say, I take 10 coins and throw them into the air simultaneously. I record the result and
then repeat the experiment a further 9 times. The results of my experiments are shown in
Figure 7.7 (which of course I simulated with a random number generator).
Ten throws of 10 coins
8
6
4
2
S1
0
1
2
3
4
5
6
7
8
9
10
Throw
Figure 7.7
Ten coins tossed 10 times
We would expect an average of 5 heads per throw but we see a significant amount of
scatter. I now repeat the ten experiments with 100 coins. The results are shown in Figure 7.8,
and you can see that there is much less scatter about the mean. The point is that there is
