27.1 Revision of basic probability and fundamental principle of counting
27.2 Experimental probability and relative frequency
The Learning Outcomes covered in this unit are contained in the following sections:
SP.2c
Key words Experimental probability
Frequency Relative frequency
27.1 Revision of basic probability and fundamental principle of counting
By the end of this section you should: ● recall and understand information from Probability 1
On a production line, light bulbs are tested to see how long they will last. After testing 1000 light bulbs, it is found that 980 will work for more than 1 600 hours.
Thomas purchases a light bulb. What is the relative frequency that the light bulb will:
(a) work for more than 1 600 hours? (b) not work for more than 1 600 hours?
Probability 2
Something to think about …
You have already studied basic probability in Section A, Unit 6. This is known as the theoretical probability of an event occurring.
For example, if you roll a die, the probability of obtaining the number 5 can be calculated in theory as:
P (E) = number of outcomes favourable to that event
For a fair six-sided die: ● ●
●
_________________________________ number of possible outcomes
Number of possible outcomes = 6
Number of outcomes favourable for throwing a fi ve = 1 6
P (throwing a fi ve) = 1 _
You have also studied the fundamental principal of counting (FPoC):
When there are m ways to do one thing, and n ways to do another, then there are m × n ways of doing both.
Be sure you are familiar with the material covered in Section A, Unit 6 before attempting the following practice questions.