Download 4-2 Addition Rules for Probability

4-2
Addition Rules for Probability
Note: This PowerPoint is only a summary and your main source should be the book.
4-3
The Multiplication Rules and
Conditional Probability
•Box A contains 4 red balls and 2 white balls. Box B contains 2 red
balls, 2 white balls. A die is rolled first and if the outcome is an even
number a ball is chosen at random from Box A, and if the outcome is
an odd number a ball is randomly chosen from Box B.
Find the probability that a red ball is chosen?
2
9
7
12
6
24
2
12
Note: This PowerPoint is only a summary and your main source should be the book.
*box1 contains 20% defective transistors,box2 contains 30%
defective transistors, and box3 contains 50% defective
transistors. A die is rolled. If the number that appears is
greater than 3, a transistor is selected from 1. If the
number is less than 3, a transistor is selected from 2. If the
number is 3, a transistor is selected from box3 . Find the
probability of selecting a defective transistor.
a) 0.028
b) 1
00
c) 0.283
d) 0.03
* A die is rolled. What is the probability that the number
rolled is greater than 2 and even number?
1/3
Male
Female
Total
Doctor
4
12
16
Physiotherapy
6
14
20
Nurse
9
11
20
Total
19
37
56
•Find the probability that the employee is a doctor or a female.
16 37 12
𝑝 𝑎 𝑑𝑜𝑐𝑡𝑜𝑟 𝑜𝑟 𝐹𝑒𝑚𝑎𝑙𝑒 =
+
−
56 56 56
•Find the probability that the employee is a physiotherapy.
20
𝑝 𝑎 𝑝ℎ𝑦𝑠𝑖𝑜𝑡ℎ𝑒𝑟𝑎𝑝𝑦 =
56
•Find the probability that the employee is a nurse and a male.
𝑝 𝑎 𝑛𝑢𝑟𝑠𝑒 𝑎𝑛𝑑 𝑎 𝑚𝑎𝑙𝑒 =
9
56
•Find the probability that the employee is a doctor given that he
a male .
𝑝 𝑎 𝑑𝑜𝑐𝑡𝑜𝑟∩ 𝑎 𝑚𝑎𝑙𝑒 4 56
𝑝 𝑎 𝑑𝑜𝑐𝑡𝑜𝑟|𝑎 𝑚𝑎𝑙𝑒 =
p(𝑎 𝑚𝑎𝑙𝑒)
=19
56
Note: This PowerPoint is only a summary and your main source should be the book.
It is reported that 27% of working women use computers at
work. Choose 5 working women at random .
1)
2)
3)
Find the probability that at least 1 use a computer at
work.= 1 − 𝑝 𝑛𝑜𝑡 𝑢𝑠𝑒 5 = 1 − 1 − 0.27 5
Find the probability that at least 1 doesn’t use a
computer at work. = 1 − 𝑝 𝑛𝑜𝑡 𝑢𝑠𝑒 5 = 1 − 0.27
Find the probability that all 5 use a computer in their
jobs. 𝑝(𝑎𝑙𝑙 𝑢𝑠𝑒)5 = 0.27 5
5
Note: This PowerPoint is only a summary and your main source should be the book.
a) A store contains 10 toys, 6 of which are defective. If a child bought 3
toys at random, what is the probability of getting 2 defective toys?
b) A person owns a collection of 25 movies, five of which are
English. If four movies are selected at random, find the
probability that three of them are English.
c) Given nine flowers, four of which are white and five of
them are red, if two flowers are selected at random,
without replacement, what is the probability that both
flowers are
red?
d) The probability of randomly selecting 3 science books and 4
math books from 8 science books and 9 math books is
The answers: