AnswersAlgebra II - MA3111 CRUnit Test

Unit Test — Unit test Answers

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Stan guessed on all 10 questions of a multiple-choice quiz. Each question has 4 answer choices. What is the probability that he got at least 2 questions correct? Round the answer to the nearest thousandth.

Question illustration
A
0.211
B
0.244
C
0.756
D
0.944
2
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Sonia rolls a six-sided number cube 12 times and records if she rolls a 2. What is the number of trials for this binomial experiment?

A
2
B
6
C
12
D
18
3

Destiny performs a hypothesis test on a population with µ = 115 and . Her sample size is 25 with a mean of 120.4. Which of the following correctly depicts the z-statistic for this data?

Question illustration
A
0.04
B
0.90
C
3.53
D
3.93
4

For a standard normal distribution, which of the following expressions must always be equal to 1?

A
P (z less-than-or-equal-to a) minus P (negative a less-than-or-equal-to z less-than-or-equal-to z) minus P (z greater-than-or-equal-to a)
Option A
B
P (z less-than-or-equal-to a) minus P (negative a less-than-or-equal-to z less-than-or-equal-to z) + P (z greater-than-or-equal-to a)
Option B
C
P (z less-than-or-equal-to a) + P (negative a less-than-or-equal-to z less-than-or-equal-to z) minus P (z greater-than-or-equal-to a)
Option C
D
P (z less-than-or-equal-to a) + P (negative a less-than-or-equal-to z less-than-or-equal-to z) + P (z greater-than-or-equal-to a)
Option D
5

The stem-and-leaf plot below shows the number of pages each student in a class read the previous evening.Which statement is true about the data set?

Question illustration
A
Its median is greater than its mode.
B
It has a range of 52 pages.
C
The value of the first quartile is 13.
D
The data is symmetric.
6

A convenience sample differs from a voluntary sample in that

A
a convenience sample is structured based on accessibility to the researcher, and a voluntary sample is based on participant interest.
B
convenience samples survey each participant once, and voluntary samples survey each participant numerous times.
C
convenience sampling is a method of random sampling, and a voluntary sample is not.
D
convenience sampling is not a probability-based method, and voluntary sampling is.
7

The hourly wages earned by 20 employees are shown in the first box-and-whisker plot below. The person earning $15 per hour quits and is replaced with a person earning $8 per hour. The graph of the resulting salaries is shown in plot 2.Plot 1 Plot 2 How does the mean and median change from plot 1 to plot 2?

Question illustration
A
The mean and median remain the same.
B
The mean decreases, and the median remains the same.
C
The mean remains the same, and the median decreases.
D
The mean and median decrease.
8

A local weather enthusiast wants to see if the last five summers have been warmer than normal for Eloy, Arizona. From the National Oceanic and Atmospheric Administration (NOAA), he knows the 30-year average for July was 90° with a standard deviation of 2.1°. The last five summers recorded have an average of 93.5°. If he uses a = 5%, which of the following would be valid based on the data he has gathered?

A
He can conclude that the summers have been warmer than the 30-year average.
B
He can conclude that the summers will continue to be warmer for the next 10 years.
C
He does not have enough information to make a decision.
D
The average for the last five years fits with the 30-year average.
9

To conduct a survey about the type of phone service most people in Greenville prefer, 10 different blocks in the neighborhood are chosen. On these 10 blocks, 10 houses are selected at random, and then each resident of each of those houses is interviewed. This type of sampling method is

A
simple random sampling.
B
stratified sampling.
C
systematic random sampling.
D
cluster sampling.
10

For a standard normal distribution, find the approximate value of . Use the portion of the standard normal table below to help answer the question.zProbability0.000.50000.160.56360.220.58710.780.78231.000.84131.160.87701.780.96252.000.9772

Question illustration
A
22%
B
66%
C
78%
D
88%
11

You are challenged to a lucky draw game. If you draw a face card (K, Q, J) from a standard deck of cards, you earn 10 points. If you draw any other card, you lose 2 points. What is the expected value of a draw?

A
0.77
B
1.69
C
1.85
D
2.31
12

Two students have devised a dice game named “Sums” for their statistics class. The game consists of choosing to play odds or evens. Probabilities for “Sums”Roll23456789101112P(roll)Each person takes turns rolling two dice. If the sum is odd, the person playing odds gets points equal to the sum of the roll. If the sum is even, the person playing evens gets points equal to the sum of the roll. Note that the points earned is independent of who is rolling the dice.If Jessica is challenged to a game of Sums, which statement below is accurate in every aspect in guiding her to the correct choice of choosing to play odds or evens?

Question illustration
A
E(evens) will be more because there are more even numbers that result from rolling two dice. Therefore, Jessica should play evens.
B
E(odds) will be more because the probability for each odd number being rolled is greater. Therefore, Jessica should play odds.
C
E(evens) will be more because the value of the even numbers on the dice are more. Therefore, Jessica should play evens.
D
E(evens) = E(odds) because the different probabilities and values end up balancing out, creating a fair game. Therefore, Jessica may choose whichever she likes.
13

The resting heart rates for 80 women aged 46–55 in a simple random sample are normally distributed, with a mean of 71 beats per minute and a standard deviation of 6 beats per minute. Assuming a 90% confidence level (90% confidence level = z-score of 1.645), what is the margin of error for the population mean?Remember, the margin of error, ME, can be determined using the formula .

Question illustration
A
0.66
B
1.10
C
1.31
D
1.73
14

When finding the margin of error for the mean of a normally distributed population from a sample, what is the critical probability, assuming a confidence level of 58%?

A
0.21
B
0.42
C
0.58
D
0.79
15

The mean test scores with standard deviations of four English classes are given below.ClassMeanStandard DeviationMrs. Jones891.9Mrs. Rijo821.4Mr. Phan733.4Mrs. Scott906.1Which statement is most likely to be true?

A
The scores of Mrs. Scott’s class are the closest to the class mean.
B
The scores of Mr. Phan’s class are the closest to the class mean.
C
The scores of Mrs. Jones’s class are the closest to the class mean.
D
The scores of Mrs. Rijo’s class are the closest to the class mean.
16

The mean of a set of credit scores is and . Which statement must be true about z694?

Question illustration
A
z694 is within 1 standard deviation of the mean.
B
z694 is between 1 and 2 standard deviations of the mean.
C
z694 is between 2 and 3 standard deviations of the mean.
D
z694 is more than 3 standard deviations of the mean.
17

Black Marble Points

S
Since E(black) = 0.24 and E(red) = 0.16, Seth should choose to play black marbles.
E
E(red) will be twice that of E(black), so Seth should choose to play red marbles.
S
Since E(red) = E(black), it is a fair game, so it doesn’t matter which color Seth chooses.
B
Both options will lose points because there are two ways to lose points and only one way to gain points. He should choose neither color.
18

A high school student volunteers to present a report to the administration about the types of lunches students prefer. He surveys members of his class and records their choices. What type of sampling did the student use?

A
systematic random sampling
B
voluntary sampling
C
convenience sampling
D
stratified sampling
19

When making a statistical inference about the mean of a normally distributed population based on a sample drawn from that population, which of the following statements is correct, all else being equal?

A
The 68% confidence interval is wider than the 90% confidence interval.
B
The 90% confidence interval is narrower than the 95% confidence interval.
C
The 90% confidence interval is wider than the 99% confidence interval.
D
The 99% confidence interval is narrower than the 68% confidence interval.
20

The difference between an observational study and an experiment is that

A
in an observational study, only one group is studied, and in an experiment, two groups are studied.
B
in an observational study, the researchers do not control treatment, and in an experiment, they do.
C
in an experiment, cause-and-effect is analyzed, and in an observational study, it is not.
D
in an experiment, one group is studied over a short period of time, and in an observational study, the group is studied over a longer period of time.

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