Statistics homework help

Statistics homework help. Final Test (2)
Name: _______________________________________________________________________________
1. Find the standard deviation for the given sample data.
Data set: 3.6 3.8 7.0 4.8 2.7 2.8 6.6
A) 2.143 B) -2.065 C) 1.740 D) 3.027
2. For the stem and leaf plot below, what percentage of the observations are greater than 28
1 01
1 666789
2 0112344566
2 7778899999
3 01133445556
3 66678899
4 28778
A) 82.35% B) 55.76% C) 22.22% D) 31.11%
3. Consider the following set of data, and determine the sample mean
20 11 7 5 2 17 9 6 12
A) 10 B) 3 C) 8 D) None of the above
4. Many people believe that they can tell the difference between Coke and Pepsi. Other
people say that the two brands can’t be distinguished. To test this, a random sample of
20 adults was selected to participate in a test. After being blindfolded, each person
was given a small taste of either Coke or Pepsi and asked to indicate which brand soft
drink it was. If people really can’t tell the difference, the probability that at least 6
people will guess correctly is:
A) 0.979. B) 0.994
C) 0.014. D) 0.021
STA 2023 _____ Elementary Statistics
5. A soft drink company has a filling machine that can be set at different levels to
produce different average fill amounts. The company sets the machine to provide a mean
fill of more than 12 ounces. Which of the following would be the correct formulation of
the null and alternative?
A)
: 12
: 12 0
=



H A
H
B)
: 12
: 12 0

=


H A
H
C)
: 12
: 12 0


H x
H x
A
D) None of the above
6. Find the probability P( -0.36 < z < 1.43) using the standard normal distribution.
A) 0.2830 B) 0.7169 C) 0.7831 D) 0.5642
7. Use the given degree of confidence and sample data to find the margin of error
(ME) in estimating the population mean

of College students’ annual earnings.
Confidence level: 98%, ? = 12, . sample mean $197 and sample standard deviation
$39
A) $30.600 B) $25.894 C) $ 27.147 D) $30.183
8. Find the Z-score that corresponds to the value 82, when the mean is 56 and the standard
deviation is 9
A)
z = 2.89
B)
z = −2.89
C)
z = 0.57
D)
z = 3.00
9. A placement exam for entrance into math class yields a mean of 80 and a standard
deviation of 10. The distribution of the scores is a bell-shaped distribution. Use the
Empirical rule to find the percentage of scores that lie between 80 and 110
A) 49.85%
C) 68% B) 47.5%
D) 34 %
A
STA 2023 _____ Elementary Statistics
10. In a situation where the population standard deviation is known with a sample size larger than
30, and we wish to estimate the population mean with 95 percent confidence, what is the
appropriate critical value to use?
A)z = 1.64
B)z = 2.33
C) z = 1.96
D)Can’t be determined without knowing the degrees of freedom.
11. Determine which claim mentioned bellow must be tested using a right-tailed test.
A) 14% of all homeowners have a home security alarm
B) A manufacturer of grandfather clocks claims that the mean time its clocks lose is no less than 0.02
second per day.
C) A government report claims that the proportion of lung cancer that are due to smoking is at least 87%
D) The mean life of certain tire is at most 80 000 miles
12. The scores of the top ten finishers in a recent LPGA Valle of the Stars Tournament are listed below.
Find the mode score
71 67 67 72 7 72 73 68 67 67
A) 72 B) 76 C) 73 D) 67
13. Find the critical value CV to estimate the population mean µ with 98% confidence, if ? = 21
A) 2.518 B) 2.330 C) 2.582 D) 1.761
14. Which of the following would be an appropriate null hypothesis?
A) The sample proportion is not equal to 0.254
B) The sample proportion is at least 0.254
C) The population proportion is 0.254
D) Both B and C are true.
STA 2023 _____ Elementary Statistics
15. A package delivery service claims that no more than 5 percent of all packages arrive at the
address late. Assuming that the conditions for the binomial hold if a sample of size 15
packages is randomly selected and the 5 percent rate holds, what is the probability that more
than 3 packages will be delivered late?
A) 0.006 B) 0.045 C) 0.994 D) None of the above
16. A major cell phone service provider has determined that the number of minutes that its
customers use their phone per month is normally distributed with a mean equal to 445.5
minutes with a standard deviation equal to 177.8 minutes. As a promotion, the company
plans to hold a drawing to give away one free vacation to Hawaii for a customer who uses
between 397 and 420 minutes during a particular month. Based on the information
provided, what proportion of the company’s customers would be eligible for the drawing?
A) 0.2013 B) 0.1346
C) 0.0507 D) None of the above.
17. The sample size of the data whose ogive shown below
is approximately
A) 90 B) 18 C) 12 D) 34
18. For the following data set: 53 57 56 65 52 68 58 59 61 69 68 67 50 50 . Find the interquartile range
A) 9.5 B) 120.0 C) 14.0 D) 67.0
STA 2023 _____ Elementary Statistics
19. In a sales effectiveness seminar, a group of sales representatives tried two approaches to selling a
customer a new automobile: the aggressive approach and the passive approach. For 1160
customers, the following record was kept: Use it to answer questions 15, and 16
Sale No sale Total
Aggressive 270 310 580
Passive 416 164 580
Total 686 474 1160
Suppose that one customer is selected at random from all participating customer, and find them probability
that a selected customer made a No sale or used an Aggressive approach
A) 0.908 B) 0.267 C) 0.641 D) 0.500
STA 2023 _____ Elementary Statistics
20. Professional tennis player hit one hundred balls and their speeds were recorded.
Speed Number of
balls
0 – 29 4
30 – 59 16
60 – 89 60
90 – 120 20
Construct the relative frequency table that corresponds to the given frequency distribution:
A)
Speed Relative
frequency
0 – 29 0.04
30 – 59 0.20
60 – 89 0.80
90 – 120 1.00
B)
Speed Relative
frequency
0 – 29 4
30 – 59 20
60 – 89 80
90 – 120 100
C)
Speed Relative
frequency
0 – 29 0.04
30 – 59 0.16
60 – 89 0.60
90 – 120 0.20
D)None of the above

Statistics homework help