STATS assignment 1 multiple choice
As the sample size increases, the ____________. -standard deviation of the population decreases -population mean increases -standard error of the mean decreases -standard error of the mean increases
standard error of the mean decreases
Which of the following is NOT a characteristic of the normal probability distribution? -the mean, median, and mode are equal -the mean of the distribution can be negative, zero, or positive -The distribution is symmetrical -The standard deviation must be 1.
the standard deviation must be 1
Larger values of the standard deviation result in a normal curve that is _____________. -shifted to the right -shifted to the left -narrower and more peaked -wider and flatter
wider and flatter
What is the difference between a bar graph and a histogram? -There is no difference between a bar graph and a histogram -A histogram displays quantitative data, while a bar graph displays categorical data -A histogram must have space between the bars, while a bar graph has no spaces between the bars -none of these answers
A histogram displays quantitative data, while a bar graph displays categorical data
Which of the following statements is always true? a. -1 <= P(Ei) <= 1 b. P(A) = 1 - P(Ac) c. P(A) + P(B) = 1 d. both P(A) = 1 - P(Ac) and P(A) + P(B) = 1
P(A) = 1 - P(Ac)
The complement of P(A | B) is ____________. -P(A^c | B) -P(A | B^c) -P(B | A) -P(A i B)
P(A^c | B)
The appropriate probability distribution for the random variable is _____________. a. discrete b. continuous c. either discrete or continuous, depending on how the interval is defined d. not enough info to answer
discrete
There is a lower limit but no upper limit for a random variable that follows the _____________ probability distribution. -uniform -normal -exponential -binomial
exponential
The interquartile range is the difference between the ____________. -first and second quartiles -first and third quartiles -second and third quartiles -second and fourth quartiles
first and third quartiles
When sampling without replacement, the probability of obtaining a certain sample is best given by a ___________. a. hypergeometric distribution b. binomial distribution c. Poisson distribution d. normal distribution
hypergeometric distribution
To compute the probability that in a random sample of n elements, selected without replacement, we will obtain x successes, we would use the ______________. a. binomial probability distribution b. Poisson probability distribution c. hypergeometric probability distribution d. exponential probability distribution
hypergeometric probability distribution
The function used to compute the probability of x successes in n trials, when the trials are dependent, is the _____________. a. binomial probability function b. Poisson probability function c. hypergeometric probability function d. exponential probability function
hypergeometric probability function
The standard deviation of a binomial distribution is ________________. a. E(x) = pn(1 - n) b. E(x) = np(1 - p) c. E(x) = np d. none of the answers
none of the answers
Events A and B are mutually exclusive with P(A) = .3 and P(B) = .2. The probability of the complement of event B equals _____________. a. 0 b. .06 c. .70 d. none of these answers
none of these answers
If the mean of a normal distribution is negative, the standard deviation is ___________. -the standard deviation must also be negative -the variance must also be negative -a mistake has been made in the computations because the mean of a normal distribution cannot be negative -none of these answers
none of these answers
The mean of the sample __________________. -is always larger than the mean of the population from which the sample was taken -is always smaller than the mean of the population from which the sample was taken -can never be zero -none of these answers
none of these answers
The key difference between binomial and hypergeometric distributions is that with the hypergeometric distribution the ___________. a. probability of success must be less than .5 b. probability of success changes from trial to trial c. trials are independent of each other d. random variable is continuous
probability of success changes from trial to trial
The salary of employees at a company is an example of ____________. -categorical data -quantitative data -label data -time series data
quantitative data
Of five letters (A, B, C, D, and E),two letters are to be selected at random., How many possible selections are there? -20 -7 -5! -10
5!/(5 - 2)!2! = 20/2 = 10
The expected value of the random variable x is ___________. a. 2 b. 5.3 c. 10 d. 2.30
5.3
Assume that you have a binomial experiment with p = 0.5 and a sample size of 100. The expected value of this distribution is ___________. a. 0.50 b. 0.30 c. 50 d. not enough info to answer
50
An experiment consists of tossing four coins successively. The number of sample points in this experiment is __________. -16 -8 -4 -2
16
The range of probability is ______________, -any value larger than 0 -any value between minus infinity to plus infinity -0 to 1, inclusive -any value between -1 to 1
-0 to 1, inclusive
Which of the following statements about a discrete random variable and its probability distribution is true? -Values of the random variable can never be negative -Negative values of f(x) are allowed if Ef(x) = 1 -Values of f(x) must be greater than or equal to zero -The values of f(x) increase to a maximum point and then decrease
-Values of f(x) must be greater than or equal to zero
Posterior probabilities are ___________. -simple probabilities -marginal probabilities -joint probabilities -conditional probabilities
-conditional probabilities
In point estimation, data from the __________. -population are used to estimate the population parameter -sample are used to estimate the population parameter -sample are used to estimate the sample statistic -none of these answers
-sample are used to estimate the population parameter
Assume z is a standard normal random variable. Then P(z >= 2.11) equals ___________. -.4821 -.9821 -.5 -.0174
.0174
The probability there are 8 occurrences in 10 minutes is ______________. a. .0241 b. .0771 c. .1126 d. .9107
.0771
The probability there are less than 3 occurrences is _____________. a. .0659 b. .0948 c. .1016 d. .1239
.1016
If A and B are independent events with P(A) = .4 and P(B) = .6, then P(A -U B) = ____________. (-U in place of intersection symbol) a. .76 b. 1 c. .24 d. .2
.24
There is a 60% chance of getting stuck in traffic when leaving the city. On two separate days, what is the probability that you get stuck in traffic both days? a. .36 b. .60 c. 1.20 d. .30
.36
If A and B are independent events with P(A) = .4 and P(B) =.25, then P(A U B) = _____________. a. .65 b. .55 c. .10 d. not enough info to answer
.55
If P(A) = .62, P(B) = .56, and P(A U B) = .70, then P(B | A) = ______________. a. .4800 b. .7742 c. .9032 d. not enough info to answer this question
.7742
Suppose we flip a fair coin five times and each time it lands heads up. The probability of landing heads up on the next flip is ____________. -1/2 -1 -0 -none of these answers
1/2
AMR is a computer-consulting firm. The number of new clients that it has obtained each month has ranged 0 to 6. The number of new clients has the probability distribution that is shown below. NUMBER OF NEW CLIENTS PROBABILITY ______________________________________________________________________ 0 .05 1 .10 2 .15 3 .35 4 .20 5 .10 6 .05 The expected number of new clients per month is _______________. a. 6 b. 0 c. 3.05 d. 21
3.05
The expected value for a binomial probability distribution is ___________. a. E(x) = pn(1 - n) b. E(x) = p(1 - p) c. E(x) = np d. E(x) = np(1 - p)
E(x) = np
The random variable x is the new number of occurrences of an event over an interval of 10 minutes. It can be assumed 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 10 minutes is 5.3. The random variable x satisfies which of the following probability distributions? a. normal b. Poisson c. binomial d. not enough info to answer
Poisson
When dealing with the number of occurrences of an event over a specified interval of time or space and when the occurrence or nonoccurence in any interval is independent of the occurrence or nonoccurence in any other interval, the appropriate probability distribution is a _______________. a. binomial distribution b. Poisson distribution c. normal distribution d. hypergeometric probability distribution
Poisson distribution
Which of the following properties of a binomial experiment is called the stationary? a. The experiment consists of n identical trials b. Two outcomes are possible on each trial c. The probability of success is the same for each trial d. The trials are independent
The probability of success is the same for each trial
The variance for the binomial probability distribution is _______________. a. Var(x) = p(1 - p) b. Var(x) = np c. Var(x) = n(1 - p) d. Var(x) = np(1 - p)
Var(x) = np(1 - p)
A box plot is a graphical representation of data that is based on ___________. -the empirical rule -z scores -a histogram -a five number summary
a five-number summary
A standard normal deviation is a normal distribution with _______________. -a mean of 1 and standard deviation of 0 -a mean of 0 and a standard deviation of 1 -any mean and a standard deviation of 1 -any mean and any standard deviation
a mean of 0 and a standard deviation of 1
The set of all elements of interest in a study is _________________. -set notation -a set of interest -a sample -a population
a population
Any process that generates well-defined outcomes is _______, -an event -an experiment -a sample point -none of the answers is correct
an experiment
A probability distribution showing the probability of x successes in n trials, where the probability of success does not change from trial to trial, is termed a ______________. a. uniform probability distribution b. binomial probability distribution c. hypergeometric probability distribution d. normal probability distribution
binomial probability distribution
If A and B are mutually exclusive, then... a. P(A) + P(B) = 0 b. P(A) + P)B) = 1 c. P(A U B) = 0 d. P(A U B) = 1
c. P(A U B) = 0
Which of the following is NOT a measure of variability of a single variable? -range -covariance -standard deviation -coefficient of variation
covariance
A magician holds a standard deck of cards and draws one card. The probability of drawing the ace of diamonds is 1/52. What method of assigning probabilities was used? -objective method -classical method -subjective method -experimental method
classical method (assigning probabilities on the assumption of equally likely outcomes)
