STA2023 Final Exam Grade Saver fall 14 (New) Notes.pdf

8/10/2019 STA2023 Final Exam Grade Saver fall 14 (New) Notes.pdf

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STA2023

Final

Exam

Review


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==================================

This Review Covers:

One Sample Interference Hypothesis Testing

One Sample Interference Estimation

Simple Linear Regression

Central Limit Theorem

Binomial Probability

Random Variable

==================================


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Central Limit TheoremThe number of hours spent playing video games a week by the residents of Miami, FL have a mean of

10 hours with a standard deviation of 3 hours. Find the probability that if you select 42 random people,

the mean number of hours a week spent playing video games is between 9 and 15.


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The average price of a computer is $789 with a standard deviation of $ 48. Find the probability that if

27 computers are selected, their mean price is less than $650.


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A retail store's daily sales are normally distributed with a mean of $3000 and a standard deviation of

$500. Find the probability that:

a. If you randomly select a day, its sales are greater than $3120

b. If you randomly select 13 days, their mean daily sales are greater than $3120


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An organization administers a test to determine if someone is more of a workaholic or a

Partyaholic the test is designed so that the so that the mean score for Partyaholics is 40. Lets

assume that the standard deviation of Partyaholics scores on his test is 25.

Now let = 49 a. If there is a 0.24 probability of SRS of 45 Partyaholics will have a mean score below a certain

amount, what is that amount? Show you work, include an appropriately shaded and labeled

density curve and a probability statement

b. If there is a 0.24 probability of SRS of 45 Partyaholics will have a mean score that is above a

certain amount but less than 40, what is that amount? Show you work, include an

appropriately shaded and labeled density curve and a probability statement.


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one sample interference estimation

6. You want to estimate the mean number of hours people spend sleeping. In a random

sample of 12 people, the mean number of hours spent sleeping was 7.2. From past

studies, the standard deviation is known to be .75 hours, and the population is normally

distributed. Construct a 90% confidence interval of the population mean.


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You randomly select 12 video game stores and record the prices of the games sold at

each. The sample mean price is $39.00 with a standard deviation of $5. Find the 95%

confidence interval for the average price of all video games. Assume the prices are

approximately normally distributed.


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The following represents a random sample of number of shoes owned by 36 men

3 6 8 12 10 9

2 8 7 10 9 9

1 4 5 6 8 7

9 9 5 4 6 11

12 2 3 9 7 60 2 4 2 1 5

Construct a 90% confidence interval for numbers of shoes owned by all men


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one sample interference Hypothesis Testing

The monthly apartment rent in the city of Minneapolis, MN is reported to be normally

distributed with a mean of $1005/month. You collect a random sample of 15apartments

and find the mean rent to be $1100 with a standard deviation of $55. Is there enough

evidence to reject the claim at = 0.05?


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In an advertisement, a pizza shop claims that its mean delivery time is less than 30

minutes. A random selection of 37 delivery times has a sample mean of 29.5 and a

standard deviation of 3.4 minutes. Is there enough evidence to support the claim at = 0.31?


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A dietitian claim that the ice cream consumption by a person in the US is at least 3.4

pounds per year. A random sample of 50 people in the US shows that the mean ice

cream consumption by a person is 3.3 pounds per year with a standard deviation of 0.95

pounds. At = 0.05, can you reject the dietitian's claim?


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The heights of 12 moth-old baby boys is approximately normally distributed with a

mean of 29.8 inches. A random sample of 15 12 month old baby boys is collected and

displayed in the following chart. At = 0.45can it be concluded that the averageheight of baby boys differs from 29.8 inches?

25 29 302 253 26

27 28 33 32 27.3

29.8 30 32 29 29.5


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On a given night at a trucking stop on I-10, twelve Budweiser trucks had a mean weight

of 10567 lbs and we want to know if this is an indication that the mean weight of all the

trucks is less than 11,000 lbs. Weights of trucks vary with standard deviation 1000lbs.

A. Conduct an appropriate hypothesis test using the P-value approach, detail all the steps

and include a P-value picture. Use = 0.05.

B. Interpret the P-value in this context.

C. What confidence level C would make a confidence interval approach hypothesis test

equivalent to the P-value approach hypothesis test you just did? Draw an appropriately

labeled density curve with shaded in.

Interpreting the P-Value in context in a one sample z-test or t-test

If the population mean observations is indeed , then due to sampling variation alone P-value of samplemean observations are expected to be x x- units or less/more/different , when sampling SRSs of n subjects.

Confidence Level (C)

One-Sided ( < # or > # ) Two Sided ( #) = 1 2 = 1

If < then its less If > then its more If then its different


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Researchers collected a sample of 14 alligators and found that their mean length was

130.6 inches but alligators in general have a standard deviation length of 19 inches.

The researchers want to know if the mean length of all alligators is different from

125 inches.

A. Conduct an appropriate hypothesis test using the P-value approach, detail all the

steps and use 0.18

B. What confidence level would make a confidence interval approach hypothesis

test equivalent to the P-value approach test you just did? Draw an appropriately

labeled density curve with shaded in.


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During last years Black Friday sales a certain company showed a mean of $3852 in rebate dollars paid

to 99 companies. (Think of money paid to the company as a positive payment, and rebate money

returned by the company as a negative payment.) We may assume that the payment on all rebates

vary with the standard deviation $791. Complete the following hypothesis test use = 0.05. Showyour work.

(1) Assuming that

(2) =

(3)

(4):

(5): $ 4000

(6)

(7) =

(8) :


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Random VariableBon has a bucket with 25 colored balls in it. There a 15 yellow balls, 5 red balls, 2 pink balls, 2 green

balls and 1 white ball. He promises Bill that he will give him the following payout for the following balls

Yellow balls $0.00

Red balls $0.25

Pink Balls $0.50

Green balls $0.75

White balls $1.00

Make a probability table

Gain, Probability,

Make a histogram

What should Bill expect to be his payoff?

What is should Bill standard deviation?


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Let us suppose that at any given point in time, 47% of the people in the world are asleep. If we choose

three persons at random from the world's population, what is the probability that

a. Exactly one of them will be asleep?

b. Exactly two of them will be asleep?

c. Exactly three of them will be asleep?

d. Exactly none of them will be asleep?

e. At least one of them will be asleep?

f. Let X = the number of people asleep. Construct a probability distribution table for X.

g. Is the distribution of X discrete or continuous?h. What is the expected number of people asleep?


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Binominal Probability

70% of college students drink alcohol. You randomly select 13 college students and ask

each if he/she drinks alcohol. Find the probability that the number who say they drink

alcohol is:a. exactly 10

b. exactly 13

c. at least 11

d. less than 4

e. at least 4

f. at most 4

g. more than 4

h. Calculate the mean and standard deviation of X.


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For each part of this question, use the Binomial probability formula, show all your work and

round your final answer to three decimal places.

Financial Accounting students who don't go to Ednys VERY helpful final exam review, now

only have one option left for passing the final exam: Theyre just going to Christmas Tree

that Bitch. There is a one out five chance of guessing a problem right and Penior's ACG2021

Final Exam is a 20 questions multiple choice test. Let X = the number of problems guessedcorrectly among a 20 questions exam done randomly.

X is Binomially distributed because:

~ there are a fixed number of trials, n = _______________ ,

~ there are only two possible outcomes, ____________________ and ____________________ ,

~ the probability of success is the same for all students, = _____________ ,

~ trials are independent because students ____________________________________________ .

a)Write down the distribution of X.

b)What is the sample space of X?c)What is the probability of guessing correct on a quarter of the problems right?

d)What is the probability that this students gets 70% on the final exam? (Take Home)

e)What is the probability of guessing right on exactly either 1 or 2 questions?

f)What is the probability of getting at least 1 answers right?

g)What is the probability of getting at most 2 answers right?

h)If we kept on randomly selecting students who Christmas tree their accounting exam

and recording how many questions each got correct, what would be the long run mean?

i)If we kept on randomly selecting students who Christmas tree their accounting exam

and recording how many questions each got correct, what would be the long run

standard deviation?

( = ) = ( 1 )

Where = !! ( )!


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Simple Linear Regression


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The average price for special joins from in Florida had mean $145 with standard

deviation $15. The length of time these joint can keep you high for had mean 200

minutes with standard deviation 50minutes. The linear correlation between the

average joint price and length of cloud time was 0.923(super strong).II. Find regression equation for predicting joint prices from how long they keep you high.

III. Use your regression equation to predict the prices on joints who keep you high for

about 125 minutes.

IV. If the correlation was weak, say = 0.102, what would have been the predicted priceson joints kept you high for 530 minutes (a knockout joint)?

V. Would it be appropriate to use your model to predict the price of a joint from a

dispensary store in Canada? State Fuck Yeah! or Hell NO!!! and give a reason for

your answer

VI. Would it appropriate to use your model to predict prices of joints sold in Tallahassee fl

in the year 2026?State Fuck Yeah! or Hell NO!!! and give THREEreasons for youranswer

VII. Fill in the blanks with numbers to make truestatements:

a) For every degree increase in cloud time, the decrease in predicted price of joints is

__________________.

b) At zero cloud minutes, the predicted price of the joint is _______________.

c) The proportion of variation in prices joints is explained by the linear association with

cloud minutes is ____________________.

VIII. Does the y-intercept of the regression line have meaning in this context? State FuckYeah! or Hell NO!!! and give a reason for your answer

IX. If the residual for a the length of high cloud time is positive, would you expect their joint

prices to be higher or lower than predicted by the model, and why?

a. Higher, because the model is overestimating the prices of the joints.

b. Lower, because the model is underestimating the prices of the joints.

c. Higher, because the model is underestimating the prices of the joints.

d. Lower, because the model is overestimating the prices of the joints.


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STA2023 Final Exam Grade Saver fall 14 (New) Notes.pdf