Mr Kaiman's Grade 6/7 Class Blog: Language of Probability

Thought I would post some helpful information in regards to the language of probability. Please remember to complete questions 1-5 of your homework!

In day to day life there are also many other places where the language of probability is also used.

The chance of rain today is 75%.
A medication has an effectiveness of 90%
4 in 5 people agree that a particular brand of toothpaste is more effective than another.
Most likely the supermarket would have the brand of milk I want to purchase.

A probability continuum is one way to visualise the scale of likelihoods.

CERTAIN is when something will definitely occur. We assign a value of 1, or 100% to the probability of certain. For example, if I were to roll a standard dice, it is certain that I will roll a number less than 10.
IMPOSSIBLE is when something can not occur. We assign a value of 0, or 0% to the probability of impossible. For example, if I were draw a card from a standard pack of playing cards, it is impossible that I would pull out a card with a 27 on it!
Exactly half way along this continuum, we find the value of 1/2, or 50%. We call this EVEN CHANCE, or EQUALLY LIKELY. For example, if I were toss a fair coin I could get a head or a tail. Both of these have an even chance of occuring.
Anywhere between impossible and even chance (values between 0 and 50%) we call not likely, or unlikely.
Anywhere between even chance and certain (values between 50% and 100%) we call likely.
Between impossible or unlikely (0-25%) would be considered very unlikely
Between 75-99.99% would be probable/very/highly likely

Experimental probability

92 people were asked how they got to work:

The Relative Frequencies (to 2 decimal places) are:

0.38+0.46+0.09+0.08 = 1.01

(It would be exactly 1 if we had used perfect accuracy),