# Probability

by
**ReynoldsMS**

Last updated 7 years ago

** Discipline: **

Math ** Subject: **

Prob/Stat

If two events are mutually exclusive (cannot occur at the same time)Formula: P(A or B) = P(A) + P(B)If two events are not mutually exclusiveFormula: P(A or B) = P(A) + P(B) - P(B and A)

Compound Events

Conclusion:I learned probability isn't as hard as I imagined. I thought that it was going to be a much harder process but in reality it has very simple rules. I loved this project because I did a fun glogster in which it was easy to learn. I enjoyed learning about the different types of probabilities there are and how to solve each of them. They have formulas by their own and with them it is easy to solve. The real life uses are amazing because I have never thought about how often we use probability in our life. This will defenitly help me in the future.

Real Life Situation: If you are going to need surgery. Your doctor tells you that you have a 70% chance you will not survive the surgery but he tells you that you have a 40% chance to live with the disease you have. Thanks to these stadistics you can choose what to do.

Real Life Situation: What is the probability of drawing two aces from a deck of playing cards? Since there are 4 aces in a 52 deck of cards, the probability of drawing one ace is 4/52. Having removed one ace and not replacing it reduces the probabilities of drawing another ace on the second draw. The 51 cards remaining contain 3 aces and therefore the probability of drawing an ace on the second draw is 3/51. Therefore, we can multiply these probabilities and determine the probability of drawing two aces:4/52 . 3/51 = 1/221

Real Life Situation: Winning a lottery and you just need a simple formula like this:The number of winning lottery numbersThe total number of possible lottery numbersIf there will be 40 winning lottery numbers and there is a total of 100, you'll have a 40% chance of winning a lottery prize.

Probability

Independent Probability

Dependent probability occurs without replacement Formula: P(A and B) = P(A) . P(B|A)From the 20 iphones Joe has, three are defective. Three iphones are randomly selected and tested. What is the probability that al three are defective if the first and recond ones are not replaced after being selected.Probabilities: P(3 defectives)= 3/20 x 2/19 x 1/18 = 6/6840 = 1/1140

Independent probability occurs with replacement Formula: P(A and B) = P(A) . P(B)

A weather forecaster says that the probability it will rain on Saturday or Sunday is 50%, the probability it will rain on Saturday is 20%, and the probability it will rain on Sunday is 40%. What is the probability that it will rain on both Saturday and Sunday?P= (20/100)+(40/100)-(50/100)P= 10/100= 10% chance

Dependent Probability

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