Topic 3: Probability with Exercises

What is Probability?
Probability mentioned in one thing happen,
Many events cannot be foreseen with total certainty. the simplest we are able to say is however probably they're to happen, victimization the concept of chance.

TOSSING A COIN: 

When a coin is tossed, there are two possible outcomes: ·         heads (H) or ·         tails (T) We say that the probability of the coin landing H is 1                                                              2 And the probability of the coin landing T is 1                                                    2 THROWING A DICE: When a single die is thrown, there are six possible outcomes: 1, 2, 3, 4, 5, 6. The probability of any one of them is 1/6. In general: Probability of an event happening = Number of ways it happens                                                                 Total number of outcomes Example 1: There are 5 marbles in a bag: 4 are blue, and 1 is red. What is the probability that a blue marble gets picked? Number of ways it can happens: 4 (there are 4 blues) Total number of outcomes: 5 (there are 5 marbles in total) So the probability =  4                                    5                             = 0.8 Example 2: A die is rolled, find the probability that an even number is obtained. Solutions: Let us first write the sample space S of the experiment.  S = {1,2,3,4,5,6}  Let E be the event "an even number is obtained" and write it down.  E = {2,4,6}  We now use the formula of the classical probability.         P(E) = n(E)                     n(S)             = 3                       6                    = 1                       2  Example 3: Two coins are tossed find the probability that two heads are obtained. Note: Each coin has two possible outcomes H (heads) and T (Tails). Solutions: The sample space S is given by.  S = {(H,T),(H,H),(T,H),(T,T)}  Let E be the event "two heads are obtained".  E = {(H,H)}  We use the formula of the classical probability.      P(E) = n(E)                   n(S)                   =  1                      4 Here is the sample of video: -EXERCISE- !GOOD LUCK! Question 1:  A dice is thrown once. What is the probability that the score is a factor 6? a) 1/6 b) 1/2 c) 2/3 d) 1 Question 2: The diagram shows a spinner made up of a piece of card in the shape of a regular pentagon, with a toothpick pushed through its center. The five triangles are numbered from 1 to 5.  The spinner is spun until it lands on one of five edges of the pentagon. What is the probability that the number it lands on is odd? a) 1/5 b) 2/5 c) 1/2 d) 3/5 Question 3: A card is chosen at random from a deck of 52 playing cards. There are 4 Queens and 4 Kings in a deck of playing cards. What is the probability the card chosen is a Queen or a King? a) 1/13 b) 2/13 c) 1/8 d) 2/11