QBA Test 2

For a standard normal distribution, the probability of z ≤ 0 is:

.5

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:

.9190

For any continuous random variable, the probability that the random variable takes on exactly a specific value is:

0

The number of customers that enter a store during one day is an example of:

a discrete random variable.

A standard normal distribution is a normal distribution with:

a mean of 0 and a standard deviation of 1.

A weighted average of the value of a random variable, where the probability function provides weights is known as:

a probability function

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:

binomial probability distribution.

Excel's BINOM.DIST function can be used to compute:

both binomial probabilities and cumulative binomial probabilities.

Excel's NORM.S.DIST function can be used to compute:

cumulative probabilities for a standard normal z value.

The standard deviation of a standard normal distribution:

is always = 1

The highest point of a normal curve occurs at:

the mean

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

Excel's NORM.S.INV function can be used to compute:

the standard normal z value given a cumulative probability.

Which of the following is a characteristic of a binomial experiment?

the trials are independent

Whenever the probability is proportional to the length of the interval in which the random variable can assume a value, the random variable is:

uniformly distributed

Which of the following is(are) required condition(s) for a discrete probability function?

f(x) ≥ 1 for all values of x

x is a normally distributed random variable with a mean of 12 and a standard deviation of 3. The probability that x equals 19.62 is:

.0000

x is a normally distributed random variable with a mean of 22 and a standard deviation of 5. The probability that x is less than 9.7 is:

.0069

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?

.0142

z is a standard normal random variable. The P(z ≥ 2.11) equals:

.0174

Assume that you have a binomial experiment with p = .4 and a sample size of 50. The variance of this distribution is:

12

In a binomial experiment the probability of success is .06. What is the probability of two successes in seven trials?

.0555

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. Refer to Exhibit 5-11. The probability that there are 8 occurrences in ten minutes is:

.0771

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. Refer to Exhibit 5-11. The probability that there are less than 3 occurrences is:

.1016

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

.1303

The assembly time for a product is uniformly distributed between 6 to 10 minutes. The probability density function has what value in the interval between 6 and 10?

.2500

Given that z is a standard normal random variable, what is the value of z if the area to the right of z is .1112?

1.22

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. Refer to Exhibit 5-11. The expected value of the random variable x is:

5.30

The assembly time for a product is uniformly distributed between 6 to 10 minutes. The expected assembly time (in minutes) is:

8

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. Refer to Exhibit 5-11. The random variable x satisfies which of the following probability distributions?

Poisson

Excel's __________ function can be used to compute the variance of a discrete random variable.

SUMPRODUCT

Which of the following is not a characteristic of the normal probability distribution?

The standard deviation must be 1.

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. Refer to Exhibit 5-11. The appropriate probability distribution for the random variable is:

discrete

A measure of the average value of a random variable is called a(n):

expected value

The form of the continuous uniform probability distribution is:

rectangular