Question 1
(CO 4) Consider the following table:
If you created the probability distribution for these data, what would be the probability of 50-59?
0.152
0.189
0.165
0.425
Question 2
(CO 4) Consider the following table of hours worked by part-time employees. These employees must work in 5 hour blocks.
Find the mean of this variable.
17.50
20.60
17.65
18.95
Question 3
(CO 4) Consider the following table.
Find the variance of this variable.
1.49
0.67
1.41
1.99
Question 4
(CO 4) Consider the following table:
Find the standard deviation of this variable.
1.41
1.67
1.78
1.33
Question 5
(CO 4) Forty-nine percent of US teens have heard of a fax machine. You randomly select 12 US teens. Find the probability that the number of these selected teens that have heard of a fax machine is exactly six (first answer listed below). Find the probability that the number is more than 8 (second answer listed below).
0.225, 0.064
0.225, 0.111
0.640, 0.064
0.640, 0.175
Question 6
(CO 4) Ten rugby balls are randomly selected from the production line to see if their shape is correct. Over time, the company has found that 92.4% of all their rugby balls have the correct shape. If exactly 7 of the 10 have the right shape, should the company stop the production line?
Yes, as the probability of seven having the correct shape is unusual
Yes, as the probability of seven having the correct shape is not unusual
No, as the probability of seven having the correct shape is unusual
No, as the probability of seven having the correct shape is not unusual
Question 7
(CO 4) On the production line the company finds that 85.6% of products are made correctly. You are responsible for quality control and take batches of 30 products from the line and test them. What number of the 30 being incorrectly made would cause you to shut down production?
Less than 23
Less than 24
Less than 26
Less than 25
Question 8
(CO 4) Seventy-five percent of employees make judgements about their co-workers based on the cleanliness of their desk. You randomly select 8 employees and ask them if they judge co-workers based on this criterion. The random variable is the number of employees who judge their co-workers by cleanliness. Which outcomes of this binomial distribution would be considered unusual?
0, 1, 2, 3, 8
1, 2, 3
0, 1, 2, 7, 8
0, 1, 2, 3
Question 9
(CO 4) Seventy-nine percent of products come off the line ready to ship to distributors. Your quality control department selects 12 products randomly from the line each hour. Looking at the binomial distribution, if fewer than how many are within specifications would require that the production line be shut down (unusual) and repaired?
Fewer than 6
Fewer than 7
Fewer than 9
Fewer than 10
Question 10
(CO 4) Out of each 100 products, 96 are ready for purchase by customers. If you selected 21 products, what would be the expected (mean) number that would be ready for purchase by customers?
26
96
20
21
Question 11
(CO 4) Sixty-seven percent of adults have looked at their credit score in the past six months. If you select 31 customers, what is the probability that at least 25 of them have looked at their score in the past six months?
0.073
0.030
0.043
0.970
Question 12
(CO 4) One out of every 92 tax returns that a tax auditor examines requires an audit. If 70 returns are selected at random, what is the probability that less than 5 will need an audit?
0.0102
0.0009
0.9999
0.9990
Question 13
(CO 4) Thirty-eight percent of consumers prefer to purchase electronics online. You randomly select 16 consumers. Find the probability that the number who prefer to purchase electronics online is at most 5.
0.789
0.391
0.211
0.180
Question 14
(CO 5) The speed of cars on a stretch of road is normally distributed with an average 48
miles per hour with a standard deviation of 5.9 miles per hour. What is the probability that a randomly selected car is violating the speed limit of 50 miles per hour?
0.21
0.48
0.63
0.37
Question 15
(CO 5) A survey indicates that shoppers spend an average of 22 minutes with a standard deviation of 8 minutes in your store and that these times are normally distributed. Find the probability that a randomly selected shopper will spend less than 20 minutes in the store.
0.60
0.22
0.40
0.50
Question 16
(CO 5) The monthly utility bills in a city are normally distributed with a mean of $128 and a standard deviation of $23. Find the probability that a randomly selected utility bill is between $110 and $130.
0.318
0.316
0.217
0.783
Question 17
(CO 5) A restaurant serves hot chocolate that has a mean temperature of 175 degrees with a standard deviation of 8.1 degrees. Find the probability that a randomly selected cup of hot chocolate would have a temperature of less than 161 degrees. Would this outcome warrant a replacement cup (meaning that it would be unusual)?
Probability of 0.04 and would not warrant a refund
Probability of 0.96 and would not warrant a refund
Probability of 0.96 and would warrant a refund
Probability of 0.04 and would warrant a refund
Question 18
(CO 5) The yearly amounts of carbon emissions from cars in Belgium are normally distributed with a mean of 13.9 gigagrams per year and a standard deviation of 3.5 gigagrams per year. Find the probability that the amount of carbon emissions from cars in Belgium for a randomly selected year are between 11.5 gigagrams and 14.0 gigagrams per year.
0.246
0.265
0.496
0.754
Question 19
(CO 5) On average, the parts from a supplier have a mean of 97.5 inches and a standard deviation of 12.2 inches. Find the probability that a randomly selected part from this supplier will have a value between 85.3 and 109.7 inches. Is this consistent with the Empirical Rule of 68%-95%-99.7%?
Probability is 0.68, which is inconsistent with the Empirical Rule
Probability is 0.68, which is consistent with the Empirical Rule
Probability is 0.05, which is inconsistent with the Empirical Rule
Probability is 0.95, which is consistent with the Empirical Rule
Question 20
(CO 5) A process is normally distributed with a mean of 104 rotations per minute and a standard deviation of 8.2 rotations per minute. If a randomly selected minute has 129 rotations per minute, would the process be considered in control or out of control?
Out of control as this one data point is more than two standard deviations from the mean
In control as only one data point would be outside the allowable range
In control as this one data point is not more than three standard deviations from the mean
Out of control as this one data point is more than three standard deviations from the mean
Question 21
(CO 5) The soup produced by a company has a salt level that is normally distributed with a mean of 5.4 grams and a standard deviation of 0.3 grams. The company takes readings of every 10th bar off the production line. The reading points are 5.8, 5.9, 4.9, 5.2, 5.0, 4.9, 6.2, 5.1, 6.7, 6.1. Is the process in control or out of control and why?
It is in control as the values jump above and below the mean
It is in control as the data points more than 2 standard deviations from the mean are far apart
It is out of control as two of these data points are more than 2 standard deviations from the mean
It is out of control as one of these data points is more than 3 standard deviations from the mean
Question 22
(CO 5) A puck company wants to sponsor the players with the 10% quickest goals in hockey games. The times of first goals are normally distributed with a mean of 12.56 minutes and a standard deviation of 4.91 minutes. How fast would a player need to make a goal to be sponsored by the puck company?
7.65 minutes
6.27 minutes
17.47 minutes
18.85 minutes
Question 23
(CO 5) A stock’s price fluctuations are approximately normally distributed with a mean of $104.50 and a standard deviation of $20.88. You decide to purchase whenever the price reaches its lowest 20% of values. What is the most you would be willing to pay for the stock?
$122.07
$83.62
$86.93
$110.48
Question 24
(CO 5) The times that customers spend in a book store are normally distributed with a mean of 39.5 minutes and a standard deviation of 15.9 minutes. A random sample of 30 customers has a mean of 36.1 minutes. Would this outcome be considered unusual, so that the store should reconsider its displays?
No, the probability of this outcome at 0.121, would be considered usual, so there is no problem
No the probability of this outcome at 0.415 would be considered usual, so there is no problem
Yes, the probability of this outcome at 0.121, would be considered unusual, so the display should be redone
Yes, the probability of this outcome at 0.879 would be considered unusual, so the display should be redone
Question 25
(CO 5) The weights of ice cream cartons are normally distributed with a mean weight of 20 ounces and a standard deviation of 0.3 ounces. You randomly select 40 cartons. What is the probability that their mean weight is greater than 20.5 ounces?
0.579
0.421
0.897
0.103
Question 26
(CO 5) Recent test scores on the Law School Admission Test (LSAT) are normally distributed with a mean of 162.4 and a standard deviation of 15.9. What is the probability that the mean of 12 randomly selected scores is less than 161?
0.620
0.465
0.535
0.380
Question 27
(CO 5) The mean annual salary for intermediate level executives is about $74000 per year with a standard deviation of $2000. A random sample of 36 intermediate level executives is selected. What is the probability that the mean annual salary of the sample is between $71000 and $73500?
0.885
0.067
0.933
0.334
Question 28
(CO 4) The probability of someone ordering the daily special is 71%. If the restaurant expected 65 people for lunch, how many would you expect to order the daily special?
46
34
51
35