AnswersAZ-Common Core Algebra II BStatistical Inferences

Statistical Inferences — Unit test Answers

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Laila guesses on all 20 questions of a multiple-choice test. Each question has 4 answer choices. What is the probability of a success and a failure for this experiment?

A
;
Option A
B
;
Option B
C
;
Option C
D
;
Option D
2
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Vladimir rolls a six-sided number cube 36 times. If getting a 3 is a success, what is the probability of a success?

A
One-sixth
Option A
B
One-third
Option B
C
Two-thirds
Option C
D
Five-sixths
Option D
3

The distribution of the values of a population is shown below, and a simple random sample is drawn from the population. Based on this information alone, can the sample be used to make inferences about the population?

Question illustration
A
No, because the population values appear to be normally distributed.
B
No, because the population values do not appear to be normally distributed.
C
Yes, because the population values appear to be normally distributed.
D
Yes, because the population values do not appear to be normally distributed.
4

A utility company hires pollsters to knock on random doors in different parts of town to survey residents about the cost of their electric bill. Would this study be biased? Why or why not?

A
No, it is not biased. All residents of the town will have the opportunity to respond.
B
Yes, it is biased. Some of the residents who are surveyed may not want to respond to someone who knocks at their door.
C
No, it is not biased. All residents who are surveyed will want to respond.
D
Yes, it is biased. Only certain parts of the town were surveyed.
5

The number of absences for one week for all students at a high school were compiled, and the probability distribution below was created. What is the probability in any given week that a randomly selected student will be absent no more than one day?Probability DistributionDays Absent: XProbability: P(X)00.7810.1420.0330.014050.04

A
0.08
B
0.14
C
0.78
D
0.92
6

The graph below shows the amount of time Misha spent outside over a 30-day period. How might the graph be considered misleading?

Question illustration
A
The x-scale is different from the y-scale.
B
The x-interval makes the data appear skewed.
C
The y-scale is too large for the data set.
D
The y-interval shows exponential increase rather than linear increase.
7

The histogram below shows the average number of days per year in 117 Oklahoma cities where the high temperature was greater than 90 degrees Fahrenheit.Which is an accurate comparison?

Question illustration
A
The mean is likely greater than the median because the data is skewed to the right.
B
The mean is likely greater than the median because the data is skewed to the left.
C
The median is likely greater than the mean because the data is skewed to the right.
D
The median is likely greater than the mean because the data is skewed to the left.
8

Weston completed a hypothesis test and found that he could not reject the null hypothesis. Which of the following is a valid reason for his conclusion?

A
The z-statistic is less than 0.
B
The z-statistic lies in the critical region.
C
The z-statistic is greater than 0.
D
The z-statistic lies outside the critical region.
9

A scientist calculated the mean and standard deviation of a data set to be and . She then found that she was missing one data value from the set. She knows that the missing data value was exactly 3 standard deviations away from the mean. What was the missing data value?

Question illustration
A
129
B
147
C
360
D
369
10

A local newspaper compiles data on the number of days, X, people in a neighborhood receive the newspaper. The probability distribution for the data is shown in the table below. What is the probability that a randomly chosen person receives the newspaper at least one day per week?

Question illustration
A
16%
B
33%
C
41%
D
83%
11

Car insurance companies want to keep track of the average cost per claim. The current data in use for Auto Insurance R Us is an average of $2,200 for each claim with a standard deviation of $500. With this average, the company can stay competitive with rates but not lose money. However, the statistician for the company believes that the cost of the average claim has increased. He pulled 40 recent claims and found the average to be $2,350. Which most restrictive level of significance would suggest that the company should raise rates? Upper-Tail Valuesa5%2.5%1%Critical z-values1.651.962.58

A
1%
B
2.5%
C
5%
D
10%
12

Veronique has a spinner with three sections of equal size, red (r), green (g), and blue (b).The spinner is spun twice. The sample space for the possible outcomes is S = {rr, rb, rg, gr, gg, gb, br, bg, bb}. If the number of times red is spun is the random variable, X, which graph represents the probability distribution?

A
A probability distribution has number of times on the x-axis and probability on the y-axis. The probability of 0 times is 0.43; 1 time is 0.43; 2 times is 0.1.
Option A
B
A probability distribution has number of times on the x-axis and probability on the y-axis. The probability of 0 times is 0.33; 1 time is 0.33; 2 times is 0.33.
Option B
C
A probability distribution has number of times on the x-axis and probability on the y-axis. The probability of 0 times is 0.55; 1 time is 0.32; 2 times is 0.11.
Option C
D
A probability distribution has number of times on the x-axis and probability on the y-axis. The probability of 0 times is 0.5; 1 time is 0.38; 2 times is 0.12.
Option D
13

The histogram below shows the estimated monthly salaries of company employees with different years of experience. How might the graph be misleading?

Question illustration
T
The scale on the y-axis overemphasizes the difference in salaries between different experience levels.
T
The scale on the y-axis underemphasizes the difference in salaries between different experience levels.
T
The scale on the x-axis overemphasizes the difference in salaries between different experience levels.
T
The scale on the x-axis underemphasizes the difference in salaries between different experience levels.
14

Which set of population data is the least dispersed from its mean?

A
2, 3, 2, 9
B
4, 0, 4, 0
C
6, 2, 2, 2
D
9, 3, 5, 3
15

Opal is collecting data on water levels in different parts of town. She notices that her sample data has a low-value outlier. Which statement must be true?

A
Removing the outlier will not change the spread of the graph of the data set.
B
Removing the outlier will not change the variance of the data set.
C
Removing the outlier will increase the variance of the data set.
D
Removing the outlier will decrease the spread of the graph of the data set.
16

Vladimir rolls a six-sided number cube 36 times. If getting a 3 is a success, what is the probability of a success?

A
One-sixth
Option A
B
One-third
Option B
C
Two-thirds
Option C
D
Five-sixths
Option D
17

Mrs. Gomes found that 40% of students at her high school take chemistry. She randomly surveys 12 students. What is the probability that at most 4 students have taken chemistry? Round the answer to the nearest thousandth.

Question illustration
A
0.008
B
0.438
C
0.562
D
0.665
18

The proportions of multiple samples of registered voters who vote are normally distributed, with a mean proportion of 0.38 and a standard deviation of 0.0485. What is the probability that a sample chosen at random has a proportion of registered voters who vote between 0.37 and 0.39? Use the portion of the standard normal table below to help answer the question.zProbability0.000.50000.040.51600.210.58320.370.64430.380.64810.390.65171.000.8413

A
2%
B
17%
C
58%
D
65%
19

A normal distribution of data has a mean of 90 and a standard deviation of 18. What is the approximate z-score for the value 64?

A
–3.6
B
–1.4
C
1.4
D
3.6
20

The life spans of a computer manufacturer’s hard drives are normally distributed, with a mean of 3 years 6 months and a standard deviation of 9 months. What is the probability of a randomly selected hard drive from the company lasting between 2 years 3 months and 3 years 3 months? Use the portion of the standard normal table below to help answer the question.zProbability0.000.50000.230.59100.330.62930.670.74861.000.84131.330.90821.670.95252.000.9772

A
32%
B
37%
C
42%
D
95%

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