Question

The probability distribution of a discrete random variable x is shown below.

X                         0               1               2               3

P(X)                   0.25        0.40         0.20          0.15

What is the standard deviation of x?

	a.	0.9875
	b.	3.0000
	c.	0.5623
	d.	0.9937
	e.	0.6000

Each of the following are characteristics of the sampling distribution of the mean except:

	a.	The standard deviation of the sampling distribution of the mean is referred to as the standard error.
	b.	If the original population is not normally distributed, the sampling distribution of the mean will also be approximately normally distributed for small sample sizes.
	c.	If the original population is normally distributed , the sampling distribution of the mean will also be normally distributed.
	d.	All of the other answers are characteristics of the sampling distribution of the mean.
	e.	The sampling distribution of the mean has the same mean as the original population.

A survey revealed that 21.5% of the households had no checking account, 66.9% had regular checking accounts, and 11.6% had NOW accounts. Of those households with no checking account 40% had savings accounts. Of the households with regular checking accounts 71.6% had a savings account. Of the households with NOW accounts 79.3% had savings accounts.

The probability that a randomly selected one of these households with a savings account has a NOW account is:

	a.	0.1309
	b.	0.1492
	c.	0.2150
	d.	0.4000
	e.	0.1290

Which of the following are not correct concerning the probability distribution for any continuous random variable?

	a.	The range of the random variable is found on the y-axis.
	b.	The area under the curve represents the sum of probabilities for all possible outcomes.
	c.	The total area represented under the curve will be equal to 1.00.
	d.	The probability that x will take on a value between a and b will be the area under the curve between points a and b.
	e.	The vertical coordinate is the probability density function.

Question 25

If A and B are independent events with P(A)= 0.25 and P(B) =0.60, then P(B|A) is:

	a.	0.15
	b.	0.25
	c.	0.35
	d.	0.85
	e.	0.60

The standard error is:

	a.	is the same for distributions of all sample sizes.
	b.	the standard deviation of the sampling distribution
	c.	the same value as the population standard deviation
	d.	the squared value of the population variance.
	e.	is the mean of the sampling distribution.

Which of the following statements is not correct?

	a.	If event A does not occur, then its complement will occur.
	b.	Two events A and B are mutually exclusive if when event A occurs then event B cannot occur.
	c.	An intersection of events implies that at least one event in a group occurs but not necessarily all.
	d.	If all possible outcomes of an experiment are represented in a set, the set is considered exhaustive.
	e.	If events A and B occur at the same time, then A and B intersect in a Venn diagram.

The average sales per customer at a home improvement store during the past year is $75 with a standard deviation of $12. The probability that the average sales per customer from a sample of 64 customers, taken at random from this population, exceeds $77 is:

	a.	0.0918
	b.	0.4332
	c.	0.0668
	d.	0.9013
	e.	0.5000

For n=15,  π= 0.4 Cumulative Binomial table

x    0        1           2              3             4              5                6               7              8            P(X<=x)    0.0005   0.0052   0.0271   0.0905 0.2173    0.4032    0.6098    0.7869   0.9050

x                          9                10             11               12              13           14            15

P(X<=x)        0.9662      0.9907     0.9981       0.9997     1.0000         etc.

What is the probability P(X<13)?

	a.	0.3564
	b.	0.9997
	c.	0.0931
	d.	0.1181
	e.	0.0338

For n=15,  π= 0.4 Cumulative Binomial table

x                     0               1             2                3              4               5              6              7              8                P(X<=x)    0.0005   0.0052   0.0271   0.0905 0.2173    0.4032    0.6098    0.7869   0.9050

x                          9              10             11            12              13           14            15

P(X<=x)        0.9662      0.9907     0.9981       0.9997     1.0000         etc.

What is the probability P(6<X<10)?

	a.	0.0338
	b.	0.0931
	c.	0.3564
	d.	0.9997
	e.	0.1181

Question 33

         For n=15,  π= 0.4 Cumulative Binomial table

x                      0             1                2              3              4                5        6              7           8            P(X<=x)    0.0005   0.0052   0.0271   0.0905 0.2173    0.4032    0.6098    0.7869   0.9050

x                           9               10             11           12              13           1 4            15

P(X<=x)        0.9662      0.9907     0.9981       0.9997     1.0000         etc.

What is the probability P(X=8)?

	a.	0.1181
	b.	0.0931
	c.	0.9997
	d.	0.0338
	e.	0.3564

Answer 1