SOM 307 Mid-Term Dr. Akash Gupta

A health conscious student faithfully wears a device that tracks his steps. Suppose that the distribution of the number of steps he takes in a day is normally distributed with a mean of 10,000 and a standard deviation of 1,500 steps. What is the probability that less than 8000 steps were taken ?

0.091

Let X be a random variable with a Uniform distribution between 8 and 20. Find the probability that X is less than 10?

0.16

Compute the relative frequencies of Grade A for the data given in the table below: Grades Number of students A 16 B 28 C 33 D 13 Total 90

0.18

Given that P(A) = 0.3, P(A | B) = 0.4, and P(B) = 0.5, compute

0.20

A nickel and a dime are tossed. If an event is defined as a single toss of both coins where at least one head appears, what is the probability of the complement of that event?

0.25

Given that A and B are independent variables and P(A|B) = 0.7, what P(Ac)?

0.3

Reviews of call center representatives over the last three years showed that 10% of all call center representatives were rated as outstanding, 75% were rated as excellent/good, 10% percent were rated as satisfactory, and 5% were considered unsatisfactory. For a sample of 10 reps selected at random, what is the probability that 1 will be rated as unsatisfactory?

0.315

In the probability table below, which value is a marginal probability? ​ Completed Obstacle Course Level No. Yes. Total Challenging 0.4 0.3 0.7 Easy 0.1. 0.2. 0.3 Total 0.5. 0.5. 1.0

0.5

Fast food restaurants pride themselves in being able to fill orders quickly. A study was done at a local fast food restaurant to determine how long it took customers to receive their order at the drive-thru. It was discovered that the time it takes for orders to be filled is exponentially distributed with a mean of 1.5 minutes. What is the probability that it takes less than two minute to fill an order?

0.736

A bucket contains 3 red balls, 4 yellow balls, and 5 purple balls. One ball is taken from the bucket and is not replaced. Another ball is taken from the bucket. What is the probability that the first ball is red and the second ball is yellow?

1/11

A survey of 100 random high school students finds that 85 students watched the Super Bowl, 25 students watched the Stanley Cup Finals, and 20 students watched both games. How many students did not watch either game?

10

A multiple regression model has the form (y hat)= 10 + 2x1 + 12x2. As x2increases by 1 unit (holding x 1 constant), y^ is expected to increase by how many units?

12

Compute the 50th percentile for the following data. You may use excel if you want. 10, 15, 17, 21, 25, 12, 16, 11, 13, 22

15.5

A health conscious student faithfully wears a device that tracks his steps. Suppose that the distribution of the number of steps he takes in a day is normally distributed with a mean of 10,000 and a standard deviation of 1,500 steps. What percent of the days does he exceed 13,000 steps?

2.28%

Below is a histogram for the number of days that it took Wyche Accounting to perform audits in the last quarter of last year. What is the frequency of the 21-24 bin?

3

The number of minutes that Samantha waits to catch the bus is uniformly distributed between 0 and 15 minutes. What is the probability that Samantha has to wait less than 4.5 minutes to catch the bus?

30%

Consider the data below. What percentage of students scored grade C? Grades Number of students A 16 B 28 C 33 D 13 Total 90

37%

Below is the data for the number of days that it took Wyche Accounting to perform audits in the last quarter of last year. ​ 56, 42, 37, 29, 45, 51, 30, 25, 34, 57 ​ What is the median number of days that it took Wyche Accounting to perform audits in the last quarter of last year?

39.5

The newest model of smart car is supposed to get excellent gas mileage. A thorough study showed that gas mileage (measured in miles per gallon) is normally distributed with a mean of 75 miles per gallon and a standard deviation of 10 miles per gallon. What is the probability that, if driven normally, the car will get 75 miles per gallon or better?

50%

The random variable X is known to be uniformly distributed between 2 and 12. Compute E(X), the expected value of the distribution.

7

A game at an arcade is in the form of a large wheel that a player spins. The wheel is programmed to give 2 tickets 50% of the time, 5 tickets 25% of the time, 10 tickets 23% of the time, and 100 tickets 2% of the time. If a player spins the wheel once, what is the expected number of tickets the player will win?

7 tickets

A bucket contains 2 red balls, 4 yellow balls, and 5 purple balls. One ball is taken from the bucket and then replaced. Another ball is taken from the bucket. What is the probability that the first ball is red and the second ball is yellow?

8/121

According to company records, 5% of all automobiles brought to Geoff's Garage last year for a state-mandated annual inspection did not pass. Of the next 10 automobiles entering the inspection station, what is the probability that more than 5 will not pass inspection?

=1-BINOM.DIST(5, 10, 0.05, TRUE)

Data that are too large or too complex to be handled by standard data-processing techniques and typical desktop software are called _____.

Big data

You want to detect if there are any outliers in the variable ("Age of car (months)"), which of the following is the best visualization technique to do so?

Box plot

Please refer to the following correlation matrix. Which pair of variables show the strongest linear relationship ? The variables are: CARDPROM, NUMPROM, RAMNTALL, MAXRAMNT and LASTGIFT. Each cell in the matrix shows the correlation coefficient between two variables. For example, the correlation coefficient between CARDPROM and NUMPROM is 0.949.

CARDPROM and NUMPROM

What is the variable type for the variable "Type of the Car" ?

Categorical

Which of the following best exemplifies big data?

Cellphone owners around the world generate vast amounts of data by calling, texting, tweeting, and browsing the Web on a daily basis.

The following figure shows bar plot for the GDP of three countries in 1960. Which country shows the highest GDP among three countries?

China

_____ are collected from several entities at the same point in time.

Cross-sectional data

A retail store owner offers a discount on product A and predicts that the customers would purchase products B and C in addition to product A. Identify the technique used to make such a prediction.

Data mining

The U.S. Internal Revenue Service uses _____ to identify patterns that distinguish questionable annual personal income tax filings.

Data mining

The use of analytical techniques for better understanding patterns and relationships that exist in large data sets is _____.

Data mining

_____ refers to the degree of correlation among independent variables in a regression model.

Multicollinearity

In a normal distribution, which is greater, the mean or the median?

Neither the mean or the median (they are equal)

The __________ probability distribution can be used to estimate the number of vehicles that go through an intersection during the lunch hour.

Poisson

_____ analytics are techniques that use models, constructed from past data, to predict the future or to ascertain the impact of one variable on another.

Predictive

Let us say that we have a set of emails which are labeled as spam or not spam. Using this data, your task is to determine which future email can be potentially a spam. What kind of analytics it is ?

Predictive analytics

In the spectrum of business analytics, which is the most complex?

Prescriptive

_____ analytics use techniques that take input data and yield a best course of action.

Prescriptive

Which of the following analytical techniques helps us arrive at the best decision?

Prescriptive analytics

What is the standard method to compute the lower bound to detect outliers using the box plot ? (IQR: Inter-quartile range)

Q1 - 1.5*IQR

A survey is conducted to determine whether the age of car and type of the car influences the annual maintenance cost. A sample of 10 cars is selected and the data is shown below. The coefficient of determination (R 2 or R-squared) is 0.82. What can you infer about the quality of the regression fit ?

R-squared is close to 1, hence the fit is good.

Identify the shape of the distribution in the figure below.

Skewed right

You extracted a medical dataset with the following variables to predict ten-year risk of coronary heart disease (CHD): 1- Age 2- Gender 3- Systolic blood pressure 4- Heart rate 5- Glucose 6- Diabetese (YES or NO) 6- Ten-year risk of CHD (YES or NO) Which of the following is your target variable ?

Ten-year risk of CHD

What are the ways to approach decision making?

Tradition, rules of thumb, intuition

One of the 4 Vs of big data that refers to uncertainty due to data inconsistency and incompleteness, ambiguities, latency, deception, and model approximations is _____.

Veracity

What can we infer from the following plot ? Consider x-axis represents variable X1 and y-axis represents variable X2.

X1 and X2 have non-linear relationship

A student willing to participate in a debate competition is required to fill out a registration form. State whether each of the following information about the participant provides categorical or quantitative data. a. What is your birth month? b. Have you participated in any debate competition previously? c. If yes, in how many debate competitions have you participated so far? d. Have you won any of the competitions? e. If yes, how many have you won?

a. Categorical, b. Categorical, c. Quantitative, d. Categorical e. Qualitative

An experiment consists of determining the speed of automobiles on a highway by the use of radar equipment. The random variable in this experiment is a

continuous random variable

Corporate-level managers use ______ to summarize sales by region, current inventory levels, and other company-wide metrics all in a single screen.

data dashboards

A multiple regression model for predicted heart rate is as follows: heart rate = 10 - 0.5*(run speed) + 12*(body weight). As the run speed increases by 1 unit (holding body weight constant), heart weight is expected to ?

decrease by 0.5

In a linear regression model, the variable that is being predicted or explained is known as _____.

dependent variable

Data dashboards are a type of _____analytics.

descriptive

A variable used to model the effect of categorical independent variables in a regression model is known as a _____.

dummy variable

In the simple linear regression model, the _____ accounts for the variability in the dependent variable that cannot be explained by the linear relationship between the variables.

error term

Prediction of the mean value of the dependent variable y for values of the independent variables x1, x2, . . . , xq that are outside the experimental range is called _____.

extrapolation

Fast food restaurants pride themselves in being able to fill orders quickly. A study was done at a local fast food restaurant to determine how long it took customers to receive their order at the drive thru. It was discovered that the time it takes for orders to be filled is exponentially distributed with a mean of 1.5 minutes. What is the probability density function for the time it takes to fill an order?

f(x) = 2/3e ^-2/3

A summary of data that shows the number of observations in each of several nonoverlapping bins is called a(n) _____.

frequency distribution

A _____ is a graphical summary of data previously summarized in a frequency distribution.

histogram

A dashboard is a collection of tables, charts, and maps to help management _____ selected aspects of the company's performance.

monitor

A mathematical model that gives the best decision, subject to the situation's constraints, is an a(n) _____.

optimization model

A forecast that helps direct police officers to areas where crimes are likely to occur based on past data is an example of _____.

predictive analytics

Data-driven decision making tends to decrease a firm's _____.

risk

A _____ is used to visualize sample data graphically and to draw preliminary conclusions about the possible relationship between two quantitative variables.

scatter chart

In a simple linear regression model, y = ß0 + ß1x + ε the parameter ß1represents the _____.

slope of the true regression line

A __________ describes the range and relative likelihood of all possible values for a random variable.

statistical distribution

A mathematical procedure for using sample data to estimate regression parameters is _____.

the least squares method

If the corelation between two variables is near 0, it implies that ______.

the variables are not linearly related

Which of the following is the examples of continuous random variable ?

time

Data collected from several entities over a period of time (minutes, hours, days, etc.) are called _____.

time series data

In the graph of the simple linear regression equation, the parameter ß0represents the _____ of the true regression line.

y-intercept

A _____ determines how far a particular value is from the mean relative to the data set's standard deviation.

z-score

A manager of a fast food restaurant wants the drive-thru employee to ask every fifth customer if he or she is satisfied with the service. Who makes up the population?

All survey respondents

Which of the following is not an approach to making decisions?

Guess and check

You want to visualize the distribution of annual maintenance cost, which type of plot will help to achieve the task ?

Histogram

_____ is the most critical step of the decision-making process.

Identifying and defining the problem

_____ refers to the technology that allows data, collected from sensors in all types of machines, to be sent over the Internet to repositories where it can be stored and analyzed.

Internet of Things (IoT)

_____ acts as a representative of the population.

A sample

Scores on Ms. Bond's test have a mean of 70 and a standard deviation of 11. David has a score of 52 on Ms. Bond's test. Scores on Ms. Nash's test have a mean of 64 and a standard deviation of 6. Steven has a score of 52 on Ms. Nash's test. Which student has the higher standardized score?

David's standardized score is -1.64 and Steven's standardized score is -2.00. Therefore, David has the higher standardized score.

_____ are analytical tools that describe what has happened.

Descriptive analytics