AnswersConcepts in Probability and Statistics - MA3120 B-CRUnit Test

Unit Test — Unit test Answers

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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%
2
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The graph represents the distribution of the number of questions answered correctly on a 50-question math test.

Question illustration
A
4
B
8
C
12
D
24
3

Which could be a conditional relative frequency table?

A
A 4-column table with 3 rows. The first column has no label with entries C, D, total. The second column is labeled A with entries 0.25, 0.25, 0.50. The third column is labeled B with entries 0.25, 0.25, 0.50. The fourth column is labeled total with entries 0.50, 0.50, 1.0.
Option A
B
A 4-column table with 3 rows. The first column has no label with entries C, D, total. The second column is labeled A with entries 0.25, 0.35, 0.30. The third column is labeled B with entries 0.75, 0.65, 0.70. The fourth column is labeled total with entries 1.0, 1.0, 1.0.
Option B
C
A 4-column table with 3 rows. The first column has no label with entries C, D, total. The second column is labeled A with entries 0.75, 0.25, 0.50. The third column is labeled B with entries 0.25, 0.75, 0.50. The fourth column is labeled total with entries 0.50, 0.50, 1.0.
Option C
D
A 4-column table with 3 rows. The first column has no label with entries C, D, total. The second column is labeled A with entries 0.65, 0.35, 1.0. The third column is labeled B with entries 0.35, 0.65, 1.0. The fourth column is labeled total with entries 1.0, 1.0, 1.0.
Option D
4

The frequency table shows the results of a survey comparing the number of beach towels sold for full price and at a discount during each of the three summer months.The store owner converts the frequency table to a conditional relative frequency table by row.Which value should he use for X? Round to the nearest hundredth.

Question illustration
A
0.89
B
0.90
C
0.92
D
0.96
5

Which normal distribution has the greatest standard deviation?

A
A normal distribution is shown. The curve peaks at 96 and hits the axis at 75 and 115.
Option A
B
A normal distribution is shown. The curve peaks at 60 and hits the axis at 48 and 72.
Option B
C
A normal distribution is shown. The curve peaks at 16 and there is area under the curve at all points.
Option C
D
A normal distribution is shown. The curve peaks at 32 and hits the axis at 28 and 38.
Option D
6

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
7

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
8

Ms. Johnson uses a statistics program to analyze all the data collected by her students during a lab experiment about acceleration due to gravity. The program reports =31.5 and .What is the variance of the data? Round to the nearest tenth.

Question illustration
A
1.6
B
2.5
C
5.6
D
6.3
9

In Juneau, Alaska, the 30-year annual snowfall average is 86.7 inches with a standard deviation of 40.4 inches. The last four years saw an average annual snowfall of 115.7 inches, 62.9 inches, 168.5 inches, and 135.7 inches. Hia performs a hypothesis test on this data to determine if the next 30-year norm will have a different average if the trend from the last four years continues. She uses a significance level of 5%. Which of the following is a conclusion that she may make?

A
The z-statistic is 1.44, so the null hypothesis cannot be rejected.
B
The z-statistic is 1.68, so the null hypothesis cannot be rejected.
C
The z-statistic is 1.85, so the null hypothesis should be rejected.
D
The z-statistic is 4.6, so the null hypothesis should be rejected.
10

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
11

The two-way frequency table represents data from a survey asking mall visitors whether they like seafood, meat, or both. Which is the joint relative frequency for mall visitors who like seafood and meat?

Question illustration
A
StartFraction 5 Over 72 EndFraction
Option A
B
StartFraction 16 Over 72 EndFraction
Option B
C
StartFraction 20 Over 72 EndFraction
Option C
D
StartFraction 31 Over 72 EndFraction
Option D
12

The lengths of a particular snake are approximately normally distributed with a given mean = 15 in. and standard deviation = 0.8 in. What percentage of the snakes are longer than 16.6 in.?

Question illustration
A
0.3%
B
2.5%
C
3.5%
D
5%
13

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
14

The residents of three towns were polled to find the percentage of residents who take a vacation in the summer or in the winter. Which is the joint relative frequency of those in Town 2 who take a summer vacation? Round the answer to the nearest percent.

Question illustration
A
7%
B
10%
C
25%
D
75%
15

Which value for R in the table would most likely indicate an association between the conditional variables?

Question illustration
A
0.09
B
0.10
C
0.13
D
0.79
16

The graph shows the distribution of hand lengths, in centimeters, of the members of an orchestra.

Question illustration
A
1
B
2
C
4
D
5
17

The annual salaries of all employees at a financial company are normally distributed with a mean = $34,000 and a standard deviation = $4,000. What is the z-score of a company employee who makes an annual salary of $28,000?

Question illustration
A
–5
B
–3.5
C
–1.5
D
1.5
18

Which values are correct? Select three options.

A
a = 15
B
b = 18
C
c = 23
D
d = 35
E
e = 31
19

The graph below shows three different normal distributions.Which statement must be true?

Question illustration
A
Each distribution has the same mean and the same standard deviation.
B
Each distribution has the same mean and a different standard deviation.
C
Each distribution has a different mean and the same standard deviation.
D
Each distribution has a different mean and a different standard deviation.
20

A relative frequency table is made from data in a frequency table.

Question illustration
A
25%
B
33%
C
63%
D
68%

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