Question 1 Provide an appropriate response.
IQ test scores are normally distributed with a mean of 100 and a standard deviation of 15. Find the x-score that corresponds to a z-score of -1.645.
75.3
82.3
91.0
79.1
Question 2 Provide an appropriate response.
The random variable x represents the number of cars per household in a town of 1000 households. Find the probability of randomly selecting a household that has less than two cars.
0.809
0.428
0.553
0.125
Question 3 Identify the data set’s level of measurement.
numbers of touchdowns scored by a major university in five randomly selected games
4 2 4 3 4
ordinal
nominal
ratio
interval
Question 4 Determine whether the data set is a population or a sample.
The age of each employee at a local grocery store
sample
population
Question 5 Provide an appropriate response.
Fifty percent of the people that get mail-order catalogs order something. Find the probability that exactly two of 10 people getting these catalogs will order something.
0.200
11.250
0.001
0.044
Question 6 Provide an appropriate response.
A study of 1000 randomly selected flights of a major airline showed that 798 of the flights arrived on time. What is the probability of a flight arriving on time?
Question 7 Provide an appropriate response.
A random sample of 40 students has a test score with = 81.5. Assume the population standard deviation is 10.2. Construct the confidence interval for the population mean, μ if c = 0.90.
(78.8, 84.2)
(71.8, 93.5)
(51.8, 92.3)
(66.3, 89.1)
Question 8 Provide an appropriate response.
A test consists of 10 true or false questions. To pass the test a student must answer at least eight questions correctly. If the student guesses on each question, what is the probability that the student will pass the test?
0.08
0.055
0.20
0.8
Question 9 Provide an appropriate response.
Find the standardized test statistic t for a sample with n = 25, = 28, s = 3, and α = 0.005 if Round your answer to three decimal places.
1.452
1.997
1.667
1.239
Question 10 Provide an appropriate response.
The distribution of blood types for 100 Americans is listed in the table. If one donor is selected at random, find the probability of selecting a person with blood type A+.
0.45
0.68
0.4
0.34
Question 11 Provide an appropriate response.
Eight guests are invited for dinner. How many ways can they be seated at a dinner table if the table is straight with seats only on one side?
362,880
5040
40,320
1
Question 12 Provide an appropriate response.
Assume that the random variable X is normally distributed, with mean and standard deviation Compute the probability P(X > 92).
0.2420
0.1977
0.7881
0.2119
Question 13 Provide an appropriate response.
The birth weights for twins are normally distributed with a mean of 2353 grams and a standard deviation of 647 grams. Use z-scores to determine which birth weight could be considered unusual.
1200 g
2353 g
3647 g
2000 g
Question 14 Provide an appropriate response.
Use the standard normal distribution to find P(-2.25 < z < 1.25).
0.4878
0.0122
0.8822
0.8944
Question 15 Provide an appropriate response.
Find the area of the indicated region under the standard normal curve.
0.9032
0.0823
0.0968
0.4032
Question 16
Use the given frequency distribution to find the
(a) class width.
(b) class midpoints of the first class.
(c) class boundaries of the first class.
Miles (per day)
(a) 1
(b) 1
(c) 1-2
(a) 2
(b) 1
(c) 1-2
(a) 1
(b) 1.5
(c) 0.5-2.5
(a) 2
(b) 1.5
(c) 0.5-2.5
Question 17 Provide an appropriate response.
The lengths of pregnancies are normally distributed with a mean of 264 days and a standard deviation of 15 days. If 36 women are randomly selected, find the probability that they have a mean pregnancy between 264 days and 266 days.
0.5517
0.2881
0.7881
0.2119
Question 18 Identify the data set’s level of measurement.
temperatures of 73 selected refrigerators
ordinal
nominal
ratio
interval
Question 19 Provide an appropriate response.
The distribution of Master’s degrees conferred by a university is listed in the table.
Assume that a student majors in only one subject.
What is the probability that a randomly selected student with a Master’s degree majored in English or Mathematics? Round your answer to three decimal places.
0.247
0.220
0.467
0.533
Question 20 Provide an appropriate response.
Find the area of the indicated region under the standard normal curve.
0.309
0.3438
0.6562
1.309
Question 21 Provide an appropriate response.
At a raffle, 10,000 tickets are sold at $5 each for three prizes valued at $4,800, $1,200, and $400. What is the expected value of one ticket?
$0.64
-$4.36
$4.36
-$0.64
Question 22 Provide an appropriate response.
If an individual is selected at random, what is the probability that he or she has a birthday in July? Ignore leap years.
Question 23 Provide an appropriate response.
In a pizza takeout restaurant, the following probability distribution was obtained. The random variable x represents the number of toppings for a large pizza. Find the mean and standard deviation.
mean: 1.30; standard deviation: 2.38
mean: 1.54; standard deviation: 1.30
mean: 1.30; standard deviation: 1.54
mean: 1.14; standard deviation: 1.04
Question 24 Provide an appropriate response.
Find the area under the standard normal curve to the right of z = 1.
0.8413
0.1587
0.5398
0.1397
Question 25 Provide an appropriate response.
A card is drawn from a standard deck of 52 playing cards. Find the probability that the card is an ace or a black card.
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