BUAL 2600 Final Study Guide: Sample Questions

Consider a normal population with a mean of 300 and a variance of 15. What is the z value when x is 280? What is the z value when x is 280?

-1.333

Using the Z Table: P( z= 1.25)

0

Consider a normal population with a mean of 300 and a variance of 15. What is the z value when x is 280? Find P( x < 280 )

0.0918

Using the Z Table: P(z > 1.25)

0.1056

Assume that the finishing times in a New York City 10-kilometer road race are normally distributed with a mean of 61 minutes and a standard deviation of 9 minutes. Let X be a randomly selected finishing time. Find P(X > 72)

0.1112

The manager of the local grocery store has determined that, on average, 4 customers use the service desk every half-hour. Assume that the number of customers using the service desk has a Poisson distribution. What is the probability that during a randomly selected half-hour period, exactly 3 customers use the service desk?

0.1954

Suppose that historical sales records indicate that 40% of all customers who enter a discount department store make a purchase. What is the probability that 2 of the next 3 customers will make a purchase? Please use a formula to find the probability

0.288

Using the Z Table: P(0 < z < 1.25)

0.3944

Find The Probability of C: A = 0.20 B = 0.10 C = ? D = 0.25 E = 0.30

0.45

If A and B are independent events, P(A) = .2, and P(B) = .7 ,determine P(A∪B)

0.76

Using the Z Table: P(z < 1.25)

0.8944

If n = 15 and p = .4, then the standard deviation of the binomial distribution is _______.

1.897

A normal population has 99.73 percent of the population measurements within________ standard deviation(s) of the mean.

3

Data: 8,7,5,2,9,2,5,5 What is the mode?

5

Data: 8,7,5,2,9,2,5,5 What is the mean?

5.38

A random sample of size 36 is taken from a population with a mean of 50 and a standard deviation of 5. Find µx̅

50

Let A, B, and C be events and assume the following probabilities: P(A) = 0.2, P(B) = 0.3, P(C) = 0.5, P(A ∩ B) =0.06, P(A ∩ C) = 0, P(B ∩ C) = 0.5 Which two of the three events are mutually exclusive?

A,C

Which of the following is not a discrete random variable? A) the number of times a light changes red in a 10-minute cycle B) the number of minutes required to run 1 mile C) the number of defects in a sample selected from a population of 100 products D) the number of criminals found in a five-mile radius of a neighborhood

B) the number of minutes required to run 1 mile

Which of the following is a type of question used in survey research? A) dichotomous B) open-ended C) multiple-choice D) All of the other answers are correct.

D) All of the other answers are correct

Which of the following is a categorical variable? A) air temperature B) bank account balance C) daily sales in a store D) whether a person has a traffic violation

D) whether a person has a traffic violation

The measurement in a sample or a population that occurs most frequently is the ___________.

Mode

________ says that if the sample size is sufficiently large, then the sample means are approximately normally distributed

The Central Limit Theorem

________ says that if the sample size is sufficiently large, then the sample means are approximately normally distributed.

The Central Limit Theorem

A standard normal distribution has a mean of _____ and standard deviation of _____

zero, one

The ________ of two events A and B is the event that consists of the sample space outcomes belonging to both event A and event B

intersection

The Central Limit Theorem states that as the sample size increases, the distribution of the sample _______ approaches the normal distribution

means

If a population distribution is skewed to the right, then, given a random sample from that population, one would expect that the ________.

median would be less than the mean

If two events are independent, we can ________ their probabilities to determine the intersection probability.

multiply

Bar Graphs where it goes from greater to less than from the left

skewed right