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Y. M.

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Y. M.

About these flashcards

This flashcard set covers university-level microeconomics, focusing on probability, distributions, and statistical concepts like correlation, regression, and variables. It delves into questions about exam strategies, probability distributions, and real-world applications such as predicting house prices and understanding exam outcomes. Ideal for students preparing for advanced economics exams, this set helps grasp complex statistical relationships and probability theories, making it easier to tackle challenging questions and understand core economic principles.

Flashcards

44

Students

1

Language

English

Category

Micro-Economics

Level

University

Created / Updated

05.11.2017 / 05.11.2017

Case: Katie is taking an exam which consists of 10 true/false questions. Given her excellent performance in the past, the chance of getting the first five questions are 90%, but the others are 70%. All the questions are not related to each other. Calculate the probability that Katie gets no answers correct.

Although there are two different probabilities, which doesn’t look feasible, but we can apply two different binomial distributions for first five and the rest.

Yes

No

Cannot answer

Yes

No

Cannot answer

Case: James failed to study for the next stat exam. James’ exam strategy is to rely on luck for the next quiz. The quiz consists of 10 multiple-choice questions. Each question has five possible answers, only one of which is correct. All the questions are not related to each other. James plans to guess the answer to each question. Calculate the probability that James gets no answers correct.

Yes

No

Cannot answer

Yes

No

Cannot answer

Case: A supermarket sells eggs in packets of six. Their transport system from the farm to the shop is not very good, so some of the eggs get damaged on the way. If an egg gets damaged with probability p. Calculate the probability that only two eggs are damaged in a packet.

Yes

No

Cannot answer

Yes

No

Cannot answer

Case: A business owner decides to use a binomial distribution to solve one of his problems. He knows there is a 60 percent probability that he will sell one of his Red Oak floors to any customer who comes into his shop and views the wood. Out of the next 7 people who come into his shop, what is the probability that 3 people will buy a Red Oak floor?

0.09

0.19

0.24

0.09

0.19

0.24

Which probability distribution has the same mode and mean?

Uniform

Normal

Binomial

None of the above

Uniform

Normal

Binomial

None of the above

Any normally distributed values can be standardized with z-scores.

T

F

T

F

A shipment of grapefruit arrived containing the following proportions of types: 10% pink seedless, 20% white seedless, 30% pink with seeds, and 40% white with seeds.

A grapefruit is selected at random from the shipment. Find the probability of these events:

➢ It is seedless.

➢ It is white.

➢ It is pink and seedless.

➢ It is pink or seedless.

➢ It is pink, given that it is seedless.

➢ It is seedless, given that it is pink

P(sl) = 0.3

P(w) = 0.6

P(pnsl) = 0.1

P(pusl) = 0.6

P(p|sl) = 0.33

P(sl|p) = 0.25

• Box 1 contains two red balls and three green balls, and Box 2 contains four red balls and one green ball.

• One ball is randomly selected from Box 1 and placed in Box 2.

• Then one ball is randomly selected from Box 2. ➢ What is the probability that the ball selected from Box 2 is green?

0.267

• Professor French forgets to set his alarm with a probability of 0.3.

• If he sets the alarm, it rings with a probability of 0.8.

• If the alarm rings, it wakes him on time to make his first class with a probability of 0.9.

• If the alarm does not ring, he wakes in time for his first class with a probability of 0.2.

➢ What is the probability that Professor French will wake in time to make his first class tomorrow?

0.592

Does a high correlation imply there is a causality between two variables?

Yes

No

Yes

No

Which does not describe correlation accurately?

It indicates the relationship between two variables only.

It tests the linear relationship only.

The correlation equals to the slope of the linear line fitted to the data.

It indicates the relationship between two variables only.

It tests the linear relationship only.

The correlation equals to the slope of the linear line fitted to the data.

Which statement is true?

Y is an actual and Ŷ is an estimate

Y is an actual and Ŷ is an estimate

Y is an estimate and Ŷ is an actual

Y is an actual and Ŷ is an estimate

Y is an actual and Ŷ is an estimate

Y is an estimate and Ŷ is an actual

What is the error(=residual)?

Y = 40

Yhat= 20

0.5

2

20

-10

0.5

2

20

-10

Which one best describes the equation above?

Cost = 25.2 - 4.4 Capacity

Unit rise in capacity increases cost by 4.4.

Unit rise in capacity increases cost by 25.2.

-4.4 means that capacity and cost has positive relationship.

25.2 can be thought of as the y-intercept.

Unit rise in capacity increases cost by 4.4.

Unit rise in capacity increases cost by 25.2.

-4.4 means that capacity and cost has positive relationship.

25.2 can be thought of as the y-intercept.

Predict the price for a house with 2000 square feet.

house price (1000$) = 98.24833 + '.10977square feet

$98

$98,248

$317.85

$317,850

$98

$98,248

$317.85

$317,850

Regression can explain all the variations in data?

Yes

No

Yes

No

Given for a SST, which model do you prefer in regression modelling?

Smaller SSE and larger SSR

Larger SSE and smaller SSR

Smaller SSE and larger SSR

Larger SSE and smaller SSR

If you calculate SSR / SST, would it fairly explain how much a model can explain the data?

Yes

No

Yes

No

Which describes correlation and r2 the best?

Correlation measures the relationship among two or more variables.

Correlation and r2 can have values between -1 and 1.

Correlation measures how well a model fits to the data.

Both correlation and r2 cannot tell causality.

Correlation measures the relationship among two or more variables.

Correlation and r2 can have values between -1 and 1.

Correlation measures how well a model fits to the data.

Both correlation and r2 cannot tell causality.

Which one is a graph showing the number of observations in each class of a frequency distribution?

Histogram

Scatter Plot

Keyboard commands:

= turn,

= for-/backward,

= scroll

Histogram

Scatter Plot

Which one is a graph showing the relationship between a pair of variables?

Histogram

Scatter plot

Keyboard commands:

= turn,

= for-/backward,

= scroll

Histogram

Scatter plot

Toss a coin once. You will get one million and one pounds if you get a head, or you will lose one million pounds if you get a tail.
Calculate E(x)

I am happy to bet

I would not bet

Keyboard commands:

= turn,

= for-/backward,

= scroll

I am happy to bet

I would not bet

Which of the following best describes the variance?

The square of the mean

The square of the distance

The average of the squared distances between each data points and the mean

The sum of the squared distances between each data points and the mean

Keyboard commands:

= turn,

= for-/backward,

= scroll

The square of the mean

The square of the distance

The average of the squared distances between each data points and the mean

The sum of the squared distances between each data points and the mean

Which of the following best describes the following in the order of (a), (b) and (c) and the skewness?

Mean, median, mode, negatively skewed

Median, mode, mean, negatively skewed

Mode, mean, median, positively skewed

Keyboard commands:

= turn,

= for-/backward,

= scroll

Mean, median, mode, negatively skewed

Median, mode, mean, negatively skewed

Mode, mean, median, positively skewed

Which one has higher kurtosis?

Women’s height

Men’s height

Keyboard commands:

= turn,

= for-/backward,

= scroll

Women’s height

Men’s height

Guess the correlation of the following?

Non-linear relation

Close to 1

Close to 0

Close to -1

Keyboard commands:

= turn,

= for-/backward,

= scroll

Close to 1

Close to 0

Close to -1

Which one describes the correlation correctly?

It measures the strength and direction of the linear relationship between two variables.

It is greater than or equal to zero.

If there is no relationship, the correlation is -1

The best relationship is 1.

Keyboard commands:

= turn,

= for-/backward,

= scroll

It measures the strength and direction of the linear relationship between two variables.

It is greater than or equal to zero.

If there is no relationship, the correlation is -1

The best relationship is 1.

Which one is the valid interpretation?

p=0.71

There is a relatively strong positive linear relationship between test score #1 and test score #2.

Students who scored high on the first test tended to score high on second test.

Both statements above are right

Keyboard commands:

= turn,

= for-/backward,

= scroll

There is a relatively strong positive linear relationship between test score #1 and test score #2.

Students who scored high on the first test tended to score high on second test.

Both statements above are right

Is the correlation the same as the slope?

No

Yes

Keyboard commands:

= turn,

= for-/backward,

= scroll

No

Yes

The area under the curve of any probability distribution is always equal to 1.

True

False

True

False

Roll a coin. You will get one pound if you get face. Otherwise, you will lose one pound. What type of variable is the payoff?

Discrete

Continuous

None of above

Case by case

Discrete

Continuous

None of above

Case by case

The table below shows the number of televisions per household (X) from UK survey data. Is the number of televisions a discrete variable?

Yes

No

Yes

No

The probability distribution of today’s temperature

Discrete probability distribution

Continuous probability distribution

Not a probability distribution

Case by case

Discrete probability distribution

Continuous probability distribution

Not a probability distribution

Case by case

The total rainfall of the last year in the UK

Discrete probability distribution

Continuous probability distribution

Not a probability distribution

Case by case

Discrete probability distribution

Continuous probability distribution

Not a probability distribution

Case by case

The probability distribution of whether it rains or not in Bath tomorrow at 3pm.

Discrete probability distribution

Continuous probability distribution

Not a probability distribution

Case by case

Discrete probability distribution

Continuous probability distribution

Not a probability distribution

Case by case

In continuous distributions, the probability that x equals to a certain value is ____.

Zero

One

0.5

-0.5

Zero

One

0.5

-0.5

In continuous distributions, the probability that x is less than or equal to a value is the same as the probability that x is less than that value.

True

False

True

False

Which of the following is true of normal distributions?

The mean, median, and mode are all equal.

Its measure of skewness is always greater than 1.

The range of the random variable X is bounded.

Mathematical formulas make it easier to compute normal distributions.

The mean, median, and mode are all equal.

Its measure of skewness is always greater than 1.

The range of the random variable X is bounded.

Mathematical formulas make it easier to compute normal distributions.

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Flashcards

Regression can explain all the variations in data?

Yes

No

Given for a SST, which model do you prefer in regression modelling?

Smaller SSE and larger SSR

Larger SSE and smaller SSR

If you calculate SSR / SST, would it fairly explain how much a model can explain the data?

Yes

No

Which describes correlation and r2 the best?

Correlation measures the relationship among two or more variables.

Correlation and r2 can have values between -1 and 1.

Correlation measures how well a model fits to the data.

Both correlation and r2 cannot tell causality.

1
2

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