Probability Revision Quiz

“I roll a normal dice and get a 7” This event is: Impossible a) b) c) d) Unlikely Even Chance Certain L3

“A fair sided dice will land on an odd number” This event is: Impossible a) b) c) d) Unlikely Even Chance Certain L4

“It can either rain or not rain. So the probability it rains is ½”. True or False? True False L5

I have 10 sweets in a bag. 3 chocolates, 2 toffees and 5 fudges. The probability I pick a toffee at random is: a) b) c) d) L5

The letters from the word NECCESSITY are put on cards and turned over. I pick one at random. What is the probability that I pick a vowel?

I spin the following spinner a)What is the probability that the spinner lands on the pink part? a)What is the probability that the spinner lands on a blue part or a green part? b) What is the probability that the spinner lands on the red part or the green part or the yellow part or the blue part?

What is PROBABILITY? The chance of some particular thing happening (EVENT) Examples The probability of getting an A in my Math exam The probability that it rains tomorrow The probability that I win the lottery today Possible outcomes

Two types of Probability The CALCULATION of something happening In Theoretical Probability we PREDICT WHAT SHOULD BE The CALCULATION of something happening In Theoretical Probability we PREDICT WHAT SHOULD BE What ACTUALLY happens In Experimental Probability we FIND OUT WHAT IS What ACTUALLY happens In Experimental Probability we FIND OUT WHAT IS THEORETICALEXPERIMENTAL Why can the results of experimental probability be different to theoretical probability calculations? No one can tell exactly what is going to happen in the future, what happened in the past can help predict the future which is what we do in theoretical probability BUT we can never know for sure what actually happens which is what we find out in experimental probability

P(EVENT) P(Event A) = The number of ways A can happen The total number of possible ways P(Impossible event) = P(Certain event) = P(any other event) = P(event A or event B) = The sum of the probabilities of all possible outcomes = 0 1 Between 0 and 1 P(event A) + P(event B) 1

The Probability Line ALWAYS Between 0 and 1 : FRACTION, DECIMAL (or PERCENTAGE) Equally Likely

The Probability of an event NOT Happening I have a box of 7 different CDs, 3 are music CDs. What is the probability of NOT picking a music CD? In how many ways can I NOT pick a music DVD? 4 ways 4/74/7

Probability of an event NOT happening Question: What is the relationship between P(Music CD) = 3 / 7 and P(NOT Music CD) = 4 / 7 ? P(NOT Music CD) = 7 / 7 – 3 / 7 = 4 / 7 = 1 – P(Music CD) IN GENERAL The probability of an event NOT happening is found by deducting from 1 the probability of that event happening! (finding the COMPLEMENT!)

Probability of an event not happening Probability of an event NOT happening: 1 – Probability of EVENT happening Worksheet