chapter 5 quiz
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 _____. a. .0778 b. .3456 c. .5000 d. .7780
a. .0778
The probability Pete will catch fish when he goes fishing is .8. Pete is going fishing 3 days next week.The expected number of days Pete will catch fish is _____. a. 2.4 b. .6 c. 3 d. .8
a. 2.4
Which of the following is NOT a required condition for a discrete probability function? a. f(x) ≥ 0 for all values of x b. Σf(x) = 0 c. Σf(x) = 1 d. All of these answers are correct.
b. Σf(x) = 0
The probability Pete will catch fish when he goes fishing is .8. Pete is going fishing 3 days next week.The variance of the number of days Pete will catch fish is _____. a. .8 b. .16 c. 2.4 d. .48
d. .48
Probability Distribution x f(x) 10 .2 20 .3 30. .4 40 .1 The expected value of x equals _____. a. 30 b. 25 c. 100 d. 24
d. 24
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. 50 c. 0.30 d. Not enough information is given to answer this question.
b. 50
Excel's HYPGEOM.DIST function can be used to compute _____. a. bin width for histograms b. hypergeometric probabilities c. cumulative hypergeometric probabilities d. both hypergeometric probabilities and cumulative hypergeometric probabilities
b. hypergeometric probabilities
A binomial probability distribution with p = 0.3 is _____. a. bimodal b. negatively skewed c. symmetrical d. positively skewed
b. negatively skewed
The student body of a large university consists of 60% female students. A random sample of 8 students is selected.What is the probability that among the students in the sample at least 6 are male? a. .0007 b. .0413 c. .0079 d. .0499
d. .0499
The student body of a large university consists of 60% female students. A random sample of 8 students is selected.What is the probability that among the students in the sample at least 7 are female? a. .0896 b. .0168 c. .8936 d. .1064
d. .1064
The random variable x is the 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 appropriate probability distribution for the random variable is _____. a. discrete b. either discrete or continuous, depending on how the interval is defined c. continuous d. Not enough information is given to answer this question.
a. discrete
A description of how the probabilities are distributed over the values the random variable can assume is called a(n) _____. a. probability distribution b. random variable c. probability function d. expected value
a. probability distribution
A local bottling company has determined the number of machine breakdowns per month and their respective probabilities as shown below. Number of Breakdowns. Probability 0 .12 1 .38 2 .25 3 .18 4 .07 The expected number of machine breakdowns per month is _____. a. 2 b. 1.70 c. 1 d. None of these answers are correct.
b. 1.70
Assume that you have a binomial experiment with p = 0.4 and a sample size of 50. The variance of this distribution is _____. a. 3.46 b. 12 c. 20 d. Not enough information is given to answer this question.
b. 12
The number of customers who enter a store during one day is an example of _____. a. a continuous random variable b. a discrete random variable c. either a continuous or a discrete random variable, depending on the number of the customers d. either a continuous or a discrete random variable, depending on the gender of the customers
b. a discrete random variable
The variance for the binomial probability distribution is _____. a. Var(x) = p(1 − p) b. Var(x) = n(1 − p) c. Var(x) = np(1 − p) d. Var(x) = np
c. Var(x) = np(1 − p)
When using Excel's BINOM.DIST function, one should choose TRUE for the fourth input if _____. a. a probability is desired b. the correct answer is desired c. a cumulative probability is desired d. the expected value is desired
c. a cumulative probability is desired
Experimental outcomes that are based on measurement scales such as time, weight, and distance can be described by _____ random variables. a. intermittent b. uniform c. continuous d. discrete
c. continuous
The function used to compute the probability of x successes in n trials, when the trials are dependent, is the _____. a. Poisson probability function b. exponential probability function c. hypergeometric probability function d. binomial probability function
c. hypergeometric probability function
A numerical description of the outcome of an experiment is called a _____. a. variance b. probability function c. random variable d. descriptive statistic
c. random variable
The student body of a large university consists of 60% female students. A random sample of 8 students is selected.What is the random variable in this experiment? a. the student body size b. the 60% of female students c. the number of female students out of 8 d. the random sample of 8 students
c. the number of female students out of 8
Which of the following is(are) required condition(s) for a discrete probability function? a. f(x) ≥ 1 for all values of x b. f(x) < 0 c. Σf(x) = 0 d. None of these answers are correct
d. None of these answers are correct
A local bottling company has determined the number of machine breakdowns per month and their respective probabilities as shown below. Number of Breakdowns. Probability 0 .12 1 .38 2 .25 3 .18 4 .07 The probability of at least 3 breakdowns in a month is _____. a. .10 b. .30 c. .5 d. None of these answers are correct.
d. None of these answers are correct.
If you are conducting an experiment where the probability of a success is .02 and you are interested in the probability of two successes in 15 trials, the correct probability function to use is the _____. a. standard normal probability density function b. Poisson probability function c. normal probability density function d. binomial probability function
d. binomial probability function