In a survey of 1000 adults, 34% found they prefer charcoal to gas grills. The 34% would be considered a:
In a survey of 1000 adults, 34% found they prefer charcoal to gas grills. The 34% would be considered a:
Statistic
Population
Parameter
Sample
Question 2The chances of winning the Maryland lottery are one chance in twenty-two million. The probability would be considered an example of:
Inferential statistics
Experiment design
Descriptive statistics
A sample
Question 3 The milligrams of tar in 30 cigarettes would be considered:
Ordinal data
Nominal data
Interval data
Ratio data
Question 4The ratings of 50 movies would be considered:
Ordinal data
Interval data
Ratio data
Quantitative data
Question 5A researcher randomly selects and interviews fifty male and fifty female teachers. This sampling technique is called:
Cluster
Random
Convenience
Stratified
MATH221 Statistics for Decision Making
Week 2 Homework
Question 1 Given the following information, find the probability that a randomly selected student will be very short. Number of students who are very short: 45, short: 60, tall: 82, very tall: 21
28.8%
21.6%
21.0%
39.4%
Question 2Given the following information, find the probability that a randomly selected dog will be a poodle. Number of dogs who are poodles: 31, golden retrievers: 58, beagles: 20, pugs: 38
58.0%
42.0%
39.5%
21.1%
Question 3Given that there is a 21% chance it will rain on any day, what is the probability that it will rain on the first day and be clear (not rain) on the next two days?
13.1%
36.2%
16.6%
21.0%
Question 4Consider the following table. What is the probability of no?
Red Blue Total
Yes 15 21 36
No 38 13 51
Total 53 34 87
13/51
51/34
13/34
51/87
Question 5Consider the following table. What is probability of yes, given green?
Red Blue Green Total
Yes 33 44 14 91
No 18 5 28 51
Total 51 49 42 142
51/142
14/42
42/142
14/91
MATH221 Statistics for Decision Making
Week 3 Homework
Question 1Let x represent the height of first graders in a class. This would be considered what type of variable:
Nonsensical
Lagging
Discrete
Continuous
Question 2Let x represent sheets of paper in a package. This would be considered what type of variable:
Discrete
Continuous
Distributed
Inferential
Question 3Consider the following table.
Age Group Frequency
18-29 9831
30-39 7845
40-49 6869
50-59 6323
60-69 5410
70 and over 5279
If you created the probability distribution for these data, what would be the probability of 60-69?
13.0%
12.7%
15.2%
18.9%
Question 4Consider the following table.
Weekly hours worked Probability
1-30 (average=22) 0.08
31-40 (average=35) 0.16
41-50 (average=46) 0.72
51 and over (average=61) 0.04
Find the mean of this variable.
44.2
49.2
42.9
41.0
Question 5Consider the following table.
Defects in batch Probability
0 0.28
1 0.35
2 0.16
3 0.09
4 0.10
5 0.02
Find the variance of this variable.
1.83
1.35
0.85
1.44
MATH221 Statistics for Decision Making
Week 4 Homework
Question 1The length of time a person takes to decide which shoes to purchase is normally distributed with a mean of 8.54 minutes and a standard deviation of 1.91. Find the probability that a randomly selected individual will take less than 6 minutes to select a shoe purchase. Is this outcome unusual?
Probability is 0.09, which is unusual as it is less than 5%
Probability is 0.09, which is usual as it is not less than 5%
Probability is 0.91, which is unusual as it is greater than 5%
Probability is 0.91, which is usual as it is greater than 5%
Question 2In a health club, research shows that on average, patrons spend an average of 42.5 minutes on the treadmill, with a standard deviation of 4.8 minutes. It is assumed that this is a normally distributed variable. Find the probability that randomly selected individual would spent between 30 and 40 minutes on the treadmill.
Less than 1%
0.70
0.30
0.40
Question 3A tire company measures the tread on newly-produced tires and finds that they are normally distributed with a mean depth of 0.98mm and a standard deviation of 0.35mm. Find the probability that a randomly selected tire will have a depth less than 0.50mm. Would this outcome warrant a refund (meaning that it would be unusual)?
Probability of 0.91 and would warrant a refund
Probability of 0.91 and would not warrant a refund
Probability of 0.09 and would not warrant a refund
Probability of 0.09 and would warrant a refund
Question 4In an agricultural study, the average amount of corn yield is normally distributed with a mean of 189.3 bushels of corn per acre, with a standard deviation of 23.5 bushels of corn. If a study included 1200 acres, about how many would be expected to yield more than 180 bushels of corn per acre?
785 acres
654 acres
346 acres
415 acres
Question 5On average, the parts from a supplier have a mean of 31.8 inches and a standard deviation of 2.4 inches. Find the probability that a randomly selected part from this supplier will have a value between 27.0 and 36.6 inches. Is this consistent with the Empirical Rule of 68%-95%-99.7%?
Probability is 0.95, which is consistent with the Empirical Rule
Probability is 0.02, which is inconsistent with the Empirical Rule
Probability is 0.98, which is inconsistent with the Empirical Rule
Probability is 0.95, which is inconsistent with the Empirical Rule
MATH221 Statistics for Decision Making
Week 5 Homework
Question 1From a random sample of 58 businesses, it is found that the mean time the owner spends on administrative issues each week is 20.53 with a population standard deviation of 3.54. What is the 95% confidence interval for the amount of time spent on administrative issues?
(16.99, 24.07)
(19.62, 21.44)
(19.24, 24.14)
(13.45, 27.61)
Question 2If a confidence interval is given from 45.82 up to 55.90 and the mean is known to be 50.86, what is the margin of error?
10.08
2.52
45.82
5.04
Question 3If a car manufacturer wanted lug nuts that fit nearly all the time, what characteristics would be better?
wide confidence interval with low confidence level
narrow confidence interval at high confidence level
wide confidence interval with high confidence level
narrow confidence interval at low confidence level
Question 4The 95% confidence interval for these parts is 56.98 to 57.05 under normal operations. A systematic sample is taken from the manufacturing line to determine if the production process is still within acceptable levels. The mean of the sample is 57.04. What should be done about the production line?
Stop the line as it is inside the confidence interval
Stop the line as it is outside the confidence interval
Keep the line operating as it is outside the confidence interval
Keep the line operating as it is inside the confidence interval
Question 5In a sample of 41 temperature readings taken from the freezer of a restaurant, the mean is 29.7 degrees and the population standard deviation is 2.7 degrees. What would be the 80% confidence interval for the temperatures in the freezer?
(31.36, 32.44)
(24.30, 35.10)
(29.16, 30.24)
(27.00, 32.4)
MATH221 Statistics for Decision Making
Week 6 Homework
Question 1A consumer analyst reports that the mean life of a certain type of alkaline battery is no more than 63 months. Write the null and alternative hypotheses and note which is the claim.
Ho: μ = 63 (claim), Ha: μ ≥ 63
Ho: μ ≤ 63 (claim), Ha: μ > 63
Ho: μ ≤ 63, Ha: μ > 63 (claim)
Ho: μ > 63 (claim), Ha: μ ≤ 63
Question 2An amusement park claims that the average daily attendance is at least 15,000. Write the null and alternative hypotheses and note which is the claim.
Ho: μ ≥ 15000 (claim), Ha: μ < 15000
Ho: μ = 15000, Ha: μ ≤ 15000 (claim)
Ho: μ > 15000 (claim), Ha: μ = 15000
Ho: μ ≤ 15000, Ha: μ > 15000 (claim)
Question 3If the null hypothesis is rejected when it is true, this is called __________.
>a type I error
the Empirical Rule
a type II error
an alternative hypothesis
Question 4A scientist claims that the mean gestation period for a fox is less than 50.3 weeks. If a hypothesis test is performed that rejects the null hypothesis, how would this decision be interpreted?
There is enough evidence to support the scientist’s claim that the gestation period is less than 50.3 weeks
There is not enough evidence to support the scientist’s claim that the gestation period is 50.3 weeks
The evidence indicates that the gestation period is more than 50.3 weeks
There is not enough evidence to support the scientist’s claim that the gestation period is more than 50.3 weeks
Question 5A marketing organization claims that 10% of its employees are paid minimum wage. If a hypothesis test is performed that fails to reject the null hypothesis, how would this decision be interpreted?
There is sufficient evidence to support the claim that 10% of the employees are paid minimum wage
There is not sufficient evidence to support the claim that less than 10% of the employees are paid minimum wage
There is not sufficient evidence to support the claim that 10% of the employees are paid minimum wage
There is sufficient evidence to support the claim that more than 10% of the employees are paid minimum wage
MATH221 Statistics for Decision Making
Week 7 Homework
Question 1Two variables have a positive linear correlation. Does the dependent variable increase or decrease as the independent variable increases?
Cannot determine from information given
Dependent variable would remain the same
Dependent variable increases
Dependent variable decreases
Question 2What does the variable r represent?
The critical value for the correlation coefficient
The sample correlation coefficient
The coefficient of determination
The population correlation coefficient
Question 3A golfer wants to determine if the type of driver she uses each year can be used to predict the amount of improvement in her game. Which variable would be the response variable?
The improvement in her game
The type of driver
The rating of the golfer
The number of holes she plays
Question 4What would be the notation for an estimate of y for a specific value of x?
yi
y?
?
b
Question 5Which of the following graphs displays the regression equation ?=-0.91x + 11.97
Scatter plot generally from upper left to lower right where y-intercept is estimated to be around 12
Scatter plot generally from upper left to lower right where y-intercept is estimated to be around 7
Scatter plot generally from lower left to upper right where y-intercept is estimated to be around 30
Scatter plot generally from lower left to upper right where y-intercept is estimated to be around 6
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