Web Calculator Exercise 2
Daniel Alvarado
Liberty University

Z test & One sample t-test

1. A researcher is interested in whether students who attend private high schools have higher average SAT Scores than students in the general population. A random sample of 90 students at a private high school is tested and and a mean SAT score of 1030 is obtained. The average score for public high school student is 1000 (σ= 200).

a. Is this a one- or two tailed test?
This test is a one – tailed test, because the researcher wants to know that students who attend private high school will have a higher Sat score, which makes the alternative hypothesis a prediction in favor of the private school over the public high school.

b. What are H0 and Ha for this study?
The Hₒ foe the study is that the mean of the private school will be less than the mean from the public school. The Hₐ for this study is that the mean of the public school is higher than the mean for the public school.

c. Compute Z obt
To compute the Z obt we take the 200 which is the standard diviation and the 90 which is the sample size and plug in to the formula for standard error: 200divided by the square root of 90 = 21.082

d. What is the Z critical value (Z cv ) using a 0.05 alpha level?

Z cv for 005 alpha level is -1.6449

e. Should H0 be rejected? What should the researcher conclude?

H0 should not be rejected because there is not a large difference between both means.

f. Determine the 95 % confidence interval for the population mean, based on the sample mean.

Confidence level for population mean is less than 988.680 and higher than 1071.320 http://easycalculation.com/statistics/confidence-limits-mean.php

2. A researcher hypothesized that the pulse rates of long-distance athletes differ from those of other athletes. He...

...Question 1
a. Mean age = 960/20=48
b. Standard Deviation = 10.74832
Web address: http://easycalculation.com/statistics/standard-deviation.php
Frequency distribution table for denomination.
Score f(frequency)
1 1
22
4 2
5 1
6 3
7 3
8 1
9 3
10 3
12 1
N=30
c. What is the percentage of people who identify themselves as Baptist?
3/20 = .15 x 100 = 15%
What is the mode of church attendance?
5
Question 2
a. What is the Z score for a car with a price of $33,000?
Z=2.85714286
b. What is the Z score for a car with a price of $30,000?
Z=2Web address for calculator: http://www.danielsoper.com/statcalc3/calc.aspx?id=22
c. At what percentile rank is a car that sold for $30,000?
97.72%
Web calculator used: http://easycalculation.com/statistics/zscore-to-percentile.php
3. One student’s Math score was 70 and the same individual’s English score was 84. On which exam did the student do better?
Math: +3 points divided by 9.58 SD = .3132
English: + 6 points divided by 12.45 SD = .482
The student did better on the English test.
4.Suppose you administered an anxiety test to a large sample of people and obtained normally distributed scores with a mean of 45 and standard deviation of 4. Do not use web-calculator to answer...

...it is removed, does your conclusion change for the 5% significant level test in a. (carry out the final test again assuming no change in your conclusion about your test on variances in part a.) (5 marks)
2. Exercises 8-3; Question number 14 of the text (Triola). The Alberta government records freezing dates for over a hundred locations around the province. Based on average last frost dates for spring, a researcher has proposed dividing the province into early last-frost locations and late last-frost locations. Refer to Data set 17 of the text book in Appendix B. (in the CD). Use the day of year columns to test, at the 0.01 significance level, the claim that the late last frost locations have a different mean date for last spring frost than the early last-frost locations.(Use calculators to find the mean, standard deviation and variances etc)
Home work 7
2
MATH1050 Y –B FW2012
Introduction to non-Calculus based Statistics
a. Conduct the hypothesis test using the traditional method. (5 marks)
b. Conduct the hypothesis test using the p- value method. (2 marks)
Home work 7
3
MATH1050 Y –B FW2012
Introduction to non-Calculus based Statistics
c. Conduct the hypothesis test by constructing a 99% confidence interval for the difference µ1 - µ2. (2 marks)
d. Compare the results from parts a. b. and c. (1 marks)
Home work 7
4
...

...In dealing with non-pooled statistics in two different scenarios, or samples in this case. One is Standard Deviations and Assumed Equal. You can be somewhat certain that the populations have nearly equal standard deviations, and then you should use a pooled-t method. If you were really uncertain then you would use a non-pooled t-method. And with the SRS’s separate samples or normal populations, large samples are not satisfied; then the non-pooled-t methods should not be used.
As for two population means using paired samples. In each paired sample there will be a member of one population and then a member of the second group. For the simple random paired sample each one that is already selected.
Confidence intervals for one population proportion. The margin of error is quite simple; it explains how precise your estimates can be. The book states that; “the margin of error of an estimator represents the precision with which it estimates the parameter in question.” This section talks about proportions of sample (p) and population (p) determine the margin of error and then briefly mentions the sample sizes of estimating (p).
There are also hypotheses test for one population proportion. The one proportion z-test is also known as the one sample z-test for a population and the one variable proportion test. The proportion z-test can be performed by figuring out if the hypothesis is right, left, or two-tailed. Once you have figured out that you can move onto...

...Web Calculator Exercise 5
ANOVAs
1. A researcher is interested in comparing the effectiveness of three different kinds of therapy for anger problems. Eight participants are randomly assigned to three treatment conditions: Cognitive Therapy (CT), Cognitive-Behavioral Therapy (CBT), and Interpersonal Therapy (IT). All participants complete the weekly treatment for 8 weeks. Participants take an anger test before and after the 8-week treatments. Each participant’s difference score (= anger score after the treatment minus (–) anger score before the treatment) is shown in the following table. The three therapists in this experiment have equal educational levels and clinical experiences.
CT | CBT | IT |
3 | 5 | 7 |
4 | 4 | 8 |
4 | 6 | 9 |
4 | 6 | 10 |
3 | 5 | 6 |
8 | 4 | 7 |
6 | 9 | 11 |
2 | 7 | 10 |
| | |
a. What statistical test should be used to analyze the data?
The between subjects one-way randomized ANOVA should be used to analyze the data. Although the total number of participants is not indicated it would not make sense to have each participant in the three different therapies either concurrently or consecutively. The data are on an interval/ratio scale. The following assumptions are met:
● The underlying distribution is normally distributed.
● The variances among the populations being compared are
homogeneous.
● The observations are all independent of one another.
b. Identify H0 and Ha for this...

...Chapter 2 Assignment
Ryan M. Kethcart
INFOST-491 SEC-OL
Exercises
1. Consider the statement: an individual threat agent, like a hacker, can be a factor in more than one threat category. If a hacker hacks into a network, copies a few files, defaces the Web page, and steals credit card numbers, how many different threat categories does this attack fall into?
a. Overall, I believe this attack falls into four major threat categories: deliberate acts of trespass, compromises to intellectual property, technical failures, and managerial failure. Furthermore, I believe this attack would be categorized as a deliberate act of theft/trespass which compromises intellectual property due to technical and managerial failures.
b. It seems as this hacker was deliberately causing harm (i.e. copying files, vandalizing the web page, and theft of credit card numbers); due to their method of entry – hacking into a network – it leaves me to believe there were some technical failures, such as software vulnerabilities or a trap door. However, that is just one possibility as to what could have occurred. This could have also been a managerial failure; say the unknown hacker used social engineering to obtain the information to gain access to the network – proper planning and procedure execution could have potentially thwarted this hacker’s attack.
2. Using the Web, research Mafiaboy’s exploits....

...WEB SEARCH 2
1. What is the purpose of financial statement analysis? The purpose of financial statement analysis is to provide information used by the business, potential creditors and investors.
2. If a company had sales of $2,587,643 in 1998 and sales of $3,213,456 in 2003, by what percentage did sales change during this time period? 24.18%
a. If the company had a goal of increasing sales by 25% over a five-year period, did it meet its objectives? No
b. If the company had set a goal of increasing sales by 28% during the next five years, what should be the sales goal for 2008? 4,113,223.68
3. List and briefly describe the five categories of business ratios.
a. Liquidity ratios: Used to determine the company’s ability to pay off short-term debts.
(http://www.investopedia.com/terms/l/liquidityratios.asp#axzz2LMPGyktQ)
b. Activity ratios: The ability to convert different accounts into cash or sales
(http://www.investopedia.com/terms/a/activityratio.asp#axzz2LMPGyktQ)
c. Leverage ratios: Used to get an idea of a company’s method of finance or measures it’s ability to meet financial obligations.
(http://www.investopedia.com/terms/l/leverageratio.asp#axzz2LMPGyktQ)
d. Market ratios: A ratio of a company’s book value to the market value.
(http://financial-dictionary.thefreedictionary.com/Book-to-Market+Ratio)
4. Why might a company have a...

...
Lab Exercise2: Acceleration
A. Objective
This experiment will provide data to calculate the acceleration of a marble as it rolls down an incline plane over measured periods of time. To do this, the marble’s velocity will be determined and then its acceleration.
1. What is the distance between two marks in your inclined plan?
-50cm
2. What is the angle of your inclined plan with respect the horizontal?
-16degrees
3. Newton’s first law says a body at rest will remain at rest unless acted upon by an outside force, and a body in motion will continue in motion at the same speed and in the same direction unless acted upon by an outside force. What forces were acting on the marble as it traveled down the ramp?
-While traveling down the ramp the forces of gravity were acting on the marble.
4. Did the measured acceleration was about the same for the three (or four) sections of the experiment (Release point to 1st marking, to 2nd marking, etc) ?
-Yes the rates of acceleration between each section of the experiment were pretty similar.
5. Do you expect this acceleration to be constant or different for the three (or four) sections of this experiment? Explain your reasoning.
- I expect the rate of acceleration to be constant throughout the experiment being that the marble will reach its maximum acceleration and stop there.
6. By looking at the Standard Deviation results for the calculated acceleration, which...