ST 560 Midterm Module Review

If X and Y are mutually exclusive events with P(A) = 0.295, P(B) = 0.32, then P(A | B) =

0.0000

Given that z is a standard normal random variable. What is the value of z if the area to the right of z is 0.1401?

1.08

z is a standard normal random variable. What is the value of z if the area to the right of z is 0.1112?

1.22

A professor at a local university noted that the exam grades of her students were normally distributed with a mean of 73 and a standard deviation of 11. The professor has informed us that 7.93 percent of her students received grades of A. What is the minimum score needed to receive a grade of A?

88.51

Posterior probabilities are computed using

Bayes' theorem.

Which of the following is least useful in making comparisons or showing the relationships of two variables?

Stem-and-leaf display

Which difficulty of range as a measure of variability is overcome by interquartile range?

The range is influenced too much by extreme values

If we consider the simple random sampling process as an experiment, the sample mean is

a random variable.

Since the mode is the most frequently occurring data value, it

a. can never be larger than the mean. b. is always larger than the median. c. is always larger than the mean. none of these alternatives is correct.

From a population of size 500, a random sample of 50 items is selected. The mode of the sample

can be larger, smaller or equal to the mode of the population.

In a questionnaire, respondents are asked to mark their gender as male or female. Gender is an example of a(n)

categorical variable.

The counting rule that is used for counting the number of experimental outcomes when n objects are selected from a set of N objects where order of selection is important is called the

counting rule for permutations.

The total number of data items with a value less than the upper limit for the class is given by the

cumulative frequency distribution.

In a sample of 1,600 registered voters, 912 or 57% approve of the way the President is doing his job. The 57% approval is an example of

descriptive statistics.

The sampling error is the

difference between the value of the sample mean and the value of the population mean.

The entities on which data are collected are

elements.

The most common graphical presentation of quantitative data is a

histogram.

The mean of a standard normal probability distribution

is always equal to zero.

The probability that a continuous random variable takes any specific value

is equal to zero.

In computing the standard error of the mean, the finite population correction factor is used when

n/N > 0.05

The numerical value of the standard deviation can never be

negative.

The scale of measurement that is used to rank order the observation for a variable is called the

ordinal scale.

​Revised probabilities of events based on additional information are

posterior probabilities.

The weight of a candy bar in ounces is an example of

quantitative data.

​Histograms based on data on housing prices and salaries typically are

skewed to the right.

The standard deviation of is referred to as the​

standard error of the proportion.

A method of assigning probabilities based upon judgment is referred to as the

subjective method.

A perfectly balanced coin is tossed 6 times, and tails appears on all six tosses. Then, on the seventh trial

tail has same chance of appearing as the head.

When n-1 is used in the denominator to compute variance,

the data set is a sample.

The multiplication law is potentially helpful when we are interested in computing the probability of

the intersection of two events.

Temperature is an example of a variable that uses

the interval scale.

A uniform probability distribution is a continuous probability distribution where the probability that the random variable assumes a value in any interval of equal length is

the same for each interval.

For a normal distribution, a positive value of z indicates that

the sample mean is larger than the population mean.

In a scatter diagram, a line that provides an approximation of the relationship between the variables is known as a

trend line.

When a percentage of the smallest and largest values are deleted from a data set, the mean of the remaining data values is the

trimmed mean.

A characteristic of interest for the elements is called a

variable.

Since a sample is a subset of the population, the sample mean

varies around the mean of the population.

The most common type of observational study is

​a survey.

In the set of all past due accounts, let the event A mean the account is between 31 and 60 days past due and the event B mean the account is that of a new customer. The union of A and B is

​all accounts from new customers and all accounts that are from 31 to 60 days past due.

​A graphical device for depicting categorical data that have been summarized in a frequency distribution, relative frequency distribution, or percent frequency distribution is a

​bar chart.

Experiments with repeated independent trials will be described by the binomial distribution if

​each trial has exactly two outcomes whose probabilities do not change.

The binomial probability distribution is most symmetric when

​p equals 0.5.

The value of the ___________ is used to estimate the value of the population parameter

​sample statistic

The correlation coefficient ranges between

-1 and +1.

Four percent of the customers of a mortgage company default on their payments. A sample of five customers is selected. What is the probability that exactly two customers in the sample will default on their payments?

0.0142

A population has a mean of 53 and a standard deviation of 21. A sample of 49 observations will be taken. The probability that the sample mean will be greater than 57.95 is

0.0495

Forty percent of all registered voters in a national election are female. A random sample of 5 voters is selected. The probability that there are no females in the sample is

0.0778

The random variable x is the number of occurrences of an event over an interval of ten minutes. It can be assumed that the probability of an occurrence is the same in any two-time periods of an equal length. It is known that the mean number of occurrences in ten minutes is 5.3. The probability that there are less than 3 occurrences is

0.1016

z is a standard normal random variable. The P(1.05 < z < 2.13) equals

0.1303

A population has a mean of 180 and a standard deviation of 24. A sample of 64 observations will be taken. The probability that the sample mean will be between 183 and 186 is

0.1359

Of the last 100 customers entering a computer shop, 25 have purchased a computer. If the classical method for computing probability is used, the probability that the next customer will purchase a computer is

0.25

A population of size 1,000 has a proportion of 0.5. Therefore, the proportion and the standard deviation of the sample proportion for samples of size 100 are

0.5 and 0.047

The probability distribution for the daily sales at Michael's Co. is given below. Daily Sales(In $1,000s) Probability 40 0.1 50 0.4 60 0.3 70 0.2 ​ The probability of having sales of at least $50,000 is

0.90

x is a normally distributed random variable with a mean of 8 and a standard deviation of 4. The probability that x is between 1.48 and 15.56 is

0.9190

A sample of 2,500 people was asked how many cups of coffee they drink in the morning. You are given the following sample information. Cups of Coffee Frequency 0 700 1 900 2 600 3 300 2,500 ​ The variance of the number of cups of coffee is

0.96

For stem-and-leaf displays where the leaf unit is not stated, the leaf unit is assumed to equal

1.

The sum of the percent frequencies for all classes will always equal

100.

The following represents the probability distribution for the daily demand of computers at a local store. Demand Probability 0 0.1 1 0.2 2 0.3 3 0.2 4 0.2 ​ The expected daily demand is

2.2

The probability distribution for the number of goals the Lions soccer team makes per game is given below. ​ ​ Number of Goals Probability ​0 0.05 ​1 0.15 ​2 0.35 ​3 0.30 ​4 0.15 ​ The expected number of goals per game is

2.35

Random samples of size 81 are taken from an infinite population whose mean and standard deviation are 200 and 18, respectively. The distribution of the population is unknown. The mean and the standard error of the mean are

200 and 2

Random samples of size 17 are taken from a population that has 200 elements, a mean of 36, and a standard deviation of 8. The mean and the standard deviation of the sampling distribution of the sample means are

36 and 1.86.

A sample of 15 children shows their favorite restaurants: ​ McDonalds, Luppi's, Mellow Mushroom Friday's, McDonalds, McDonalds Pizza Hut, Taco Bell, McDonalds Mellow Mushroom, Luppi's, Pizza Hut McDonalds, Friday's, McDonalds Which of the following is the correct relative frequency for McDonalds?

4

Six applications for admission to a local university are checked, and it is determined whether each applicant is male or female. How many sample points exist in the above experiment?

64

The starting salaries of individuals with an MBA degree are normally distributed with a mean of $40,000 and a standard deviation of $5,000. What percentage of MBA's will have starting salaries of $34,000 to $46,000?

76.98%

The variance of a sample of 81 observations equals 64. The standard deviation of the sample equals

8

​Generally, which one of the following is the least appropriate measure of central tendency for a data set that contains outliers?

Mean

Which of the following is not a measure of variability?

Mode

In the textile industry, a manufacturer is interested in the number of blemishes or flaws occurring in each 100 feet of material. The probability distribution that has the greatest chance of applying to this situation is the

Poisson distribution.

Which of the following is a scale of measurement?

Ratio

Which of the following is not a recommended guideline for creating an effective graphical display?

Use three dimensions whenever possible, to give the display depth