基础统计学简介(英文版)

Chapter 4
Discrete Probability Distributions
Copyright 2019, 2015, 2012, Pearson Education, Inc.
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Chapter Outline
• 4.1 Probability Distributions • 4.2 Binomial Distributions • 4.3 More Discrete Probability Distributions
P(x)
nCx pxqnx
n!
pxqnx
(n x)!x!
• n = number of trials
• p = probability of success
• q = 1 – p probability of failure
• x = number of successes in n trials
surgeries)
.
Copyright 2019, 2015, 2012, Pearson Education, Inc.
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Example: Identifying and Understanding Binomial Experiments
Decide whether each experiment is a binomial experiment. If it is, specify the values of n, p, and q, and list the possible values of the random variable x. If it is not, explain why.
n = 3, p = 190, q = 110, and x = 2.

Slide 17
Example: Finding Probabilities (2 of 3)
Find the probability of being dealt 5 diamonds from a standard deck of 52 playing cards.
Solution In a standard deck of playing cards, 13 cards are diamonds. Note that it does not matter what order the cards are selected. The possible number of ways of choosing 5 diamonds out of 13 is 13C5.
Slide 7
Example: Finding presubscript n P subscript r (1 of 2)
Find the number of ways of forming four-digit codes in which no digit is repeated.
Solution:
• You need to select 4 digits from a group of 10
•
n 10, r 4
10
P4
10
10 4
10 6
10 9 8 7 6 6
5040 ways
Copyright 2019, 2015, 2012, Pearson Education, Inc.
Solution: The number of permutations is
9 9 8 7 6 5 4 3 2 1 362,880 ways

• A population might consist of all the people in Nanaimo but also may mean the PE ratios for all chemical stocks, or total assets of the 20 largest banks in North America, total collection of prices, ages, square footage of retail space in Nanaimo, and so on.
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Types of Variables
A continuous variable can assume any value within a specified range.
Examples are: The pressure in a tire, the weight of a pork chop, or the height of students in a class. Typically, continuous variables are the result of measuring something.
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Types of Statistics
Inferential Statistics: The methods used to determine something about a population, based on a sample.
EXAMPLE 3: Wine tasters sip a few drops of wine to make a decision with respect to all the wine waiting to be released for sale.

Chapter 2 Statistic ReviewA.Random variables;1.expected value:Define ：X is a discrete random variable，“ the mean （or expected value）of X " is the weighted average of the possible outcomes，where the probabilities of theoutcome serve as the appropriate weight。

p i is ith of prob。

, i=1，2，……nInterpretation: The random variable is a variable that have a probability associated with each outcome. Outcome is not controlled.Discrete random Var. ：has finite outcome，or outcome is countable infinite。

Continuous random Var。

: uncountable infinite outcome, the probability of each outcome is small because of too many numbers.For normal random Var.，probability density function is used to calculate the probability between the are。

E（)：the expectations operator,→… “ sample mean”, used to estimateThe is changed from sample to sample。