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# Z-Test

### Finding Variables From Z-Scores

Assuming that the Z-scores are normally distributed with a mean u = 0 and a standard deviation sigma = 1.0 and if: a. P (0<z<a) = 0.3212 + n/100, find a? b. P (-b<z<b) = 0.3182 - n/100, find b? Note: if the number is not in the table use the nearest number in the table.

### Statical Analysis Samples of AIT's survery responses: two-tailed test, t-teste, z-test

Using AIU's survey responses from the AIU data set, complete the following requirements in the form of a report: Perform a two-tailed hypothesis test on both the intrinsic and the extrinsic variable's data, using a .05 significance level. Begin by creating a null and an alternate statement. Use Microsoft Excel to process your

### student's raw score

A student's z-score on a organic chemistry midterm is 1.5. If the raw scores have a mean of 477 and standard deviation of 33 points, find the student's raw score to the nearest point. 527 448 749 510 Select the answer from above. Show working if possible. Need back in at most 30 minutes. Thanks

### Statistics: Does the Bowman-to-downtown route meet the STA criterion?

The policy of the Suburban Transit Authority (STA) is to add a bus route if more than 45% of the potential commuters indicate they would use the particular route. A sample of 70 commuters revealed that 39 would use a proposed route from Bowman Park to the downtown area. Does the Bowman-to-downtown route meet the STA criterion? U

### Probability for Business Analysis: Example Problem

You and your two friends decide to go to Burger King where 90% of the orders are filled accurately. What is the probability that: a) all three orders are filled accurately? b) none of the three will be filled accurately? c) at least two of the three will be filled accurately? d

### Explanation of z-test, t-test and calculation of right-tail p-value

9.54 Faced with rising fax costs, a firm issued a guideline that transmissions of 10 pages or more should be sent by 2-day mail instead. Exceptions are allowed, but they want the average to be 10 or below. The firm examined 35 randomly chosen fax transmissions during the next year, yielding a sample mean of 14.44 with a standard

### Hypothesis Testing of Mean: Z Test

A process is supposed to produce aluminum castings with a mean weight of 1.223 kg. The weights follow a normal distribution with known standard deviation 0.084 kg. (a) Set up hypotheses and a two-tailed decision rule to detect quality control violations using the .05 level of significance. (b) From the following sample of 12

### Z-Score that has 30.5% of the distributions area to its left.

Find the Z-Score that has 30.5% of the distributions area to its left. The Z-Score is ??? (round to two decimal places)

### Z-Score and Area Under the Normal Curve

Discuss the difference between a z-score and the area under the normal curve. What exactly does a z-score represent? What does the area under the graph of a normal probability distribution represent? Can a z-score be negative? Can an area be negative?

### Significance Level

10-29: According to the local union president, the mean gross income of plumbers in the Salt Lake City area follows the normal probability distribution with a mean \$45,000 and a standard deviation of \$3,000. A recent investigative reporter for KYAK TV found, for a sample of 120 plumbers, the mean gross income was \$45,000. At the

### Hypothesis Test: Z-Test for Mean

A light bulb manufacturer guarantees that the mean life of a certain type of light bulb is at least 925 hours. A random sample of 39 light bulbs has a mean life of 905 hours with a standard deviation o 55 hours. Do you have enough evidence to reject the manufacturer's claim? Use a=0.03. a) Identify the null hypothesis and alt

### Method of One Sample Z Test

The weight of a can of stewed tomatoes is listed as 16 oz., but in actuality, the weight between cans may vary, and in fact is normally distributed with mean = 16.2 ounces and standard deviation = 0.1 oz. What is the probability that a consumer buys a can whose contents are actually less than the stated weight of 16 oz.?

### Z scores test statistics

Please help discuss the z score (test statistic). Provide a listing of the major characteristics of a normal probability distribution. Include a discussion of the z score and the conversion to the number of standard deviations a z value can be away from the mean.

### Z Score to retain funding

Please show how to set this problem up. I am totally lost. Do I need to determine the Standard Deviation, etc.? Please give me a step by step way to work this problem Calculate the average student score necessary for the district to retain its federal funding. You may assume that the Standard Deviation will not change. Thi

### How to Figure Z-Scores for Tests Taken

I scored a 62 on my psychology exam and a 76 on my economics exam. I figured that my psychology exam has a mean score of 60 and my standard deviation is 5. My economics exam has a mean score of 80 and a standard deviation of 10. What would be my z-score for my psychology and economics tests? Which one is better?

### Probability - Coke and Pepsi

Please help with the following problems. Give step by step calculations. Can you can tell the difference between coke and pepsi in a blind taste test? Most people say they can and have a preference for one brand or another. However, research suggests the people can correctly identify a sample of one of these products only 60

### Normal Probability Based on Z Score

Shaver Manufacturing, Inc., offers dental insurance to its employees. A recent study by the human resource director shows the annual cost per employee per year followed the normal probability distribution, with a mean of \$1,280 and a standard deviation of \$420 per year. a. What fraction of the employees cost more than \$1,500 pe

### Z-score and Inter-Quartile Range

Sample of 10 student's ages. Student Age 1 22 2 21 3 22 4 29 5 32 6 37 7 43 8 44 9 54 10 22 Calculate the inter-quartile range Calculate the 30th percentiles Calculate the z-score. Are they any outliers in this data set?

### Hypothesis Testing: Z-Testing

3. Jiffy lube advertises a 30 minute oil change. A sample of 35 customers showed a mean change time of 34 and a standard deviation of 8.3 minutes. Assuming normality, at the α = .05 level, is there enough evidence to show the mean oil change time is different?

### Z test for population mean ..

1. A battery was designed to last an average of 30 hours in a radio. Complaints are pouring in that the batteries are junk and do not perform as expected. You test 24 batteries and find : X = 29.3 S = 2.95 Normality assumed Is there sufficient evidence to indicate premature battery failure at the &#61537; = .05 level?

### Z test for population mean problem

1. A manufacturing cell claims they make 500 parts per day. Management thinks they're wrong. Wanting to test at the 10% significance level we measured for 36 days. X = 507 S = 24 Normality assumed Determine if their claim is correct?

### The P-Value of a New Weight-Watching Company

A new weight-watching company, Weight Reducers International, advertises that those who join will lose, on the average, 10 pounds the first two weeks with a standard deviation of 2.8 pounds. A random sample of 50 people who joined the new weight reduction program revealed the mean loss to be 9 pounds. At the .05 level of signifi

### Z Test Hypothesis for Population Proportions

Speaking to a group of analysts in January 2006, a brokerage firm executive claimed that at least 70% of investors are currently confident of meeting their investment objectives. A UBS Investor Optimism Survey, conducted over the period January 2 to January 15, found that 272 of 400 investors were confident of meeting their inve

### Test of Means and proportions

1. Faced with rising fax costs, a firm issued a guideline that transmissions of 10 pages or more should be sent by 2-day mail instead. Exceptions are allowed, but they want the average to be 10 or below. The firm examined 35 randomly chosen fax transmissions during the next year, yielding a sample mean of 14.44 with a standard d

### P Value for Z test for proportions.

Please answer the following question using the P value approach. Please describe your answer in detail. The answer details are important to my understanding the P value concept. The manager of the circulation department of a newspaper claimed that 75% of subscribers would renew their subscriptions. A sample of 100 subscribe

### Z test for proportion of blower accident data

Men are usually the snow blower accident victims. There are several factors to consider, but we're going to choose the level of operating experience between men ages 21-35. We selected 32 men between the ages of 21 and 35 who'd been in snow blower accidents that caused finger amputations. 16 of the men had no experience operatin

### Hypothesis Testing: Z Test and Difference of Proportions

In the year 2000, the state of Indiana began a \$40-million renovation of its state fairgrounds, which included the building of a miniature golf course and a state-of-the-art livestock building. Now, Indiana officials are interested in learning what sorts of people are visiting the new attractions. In a survey done at this year's

### Z test for proportion of election data.

A presidential candidate's aide estimates that, among all college students, the proportion p who intend to vote in the upcoming election is at least 60%. If 137 out of a random sample of 235 college students expressed an intent to vote, can we reject the aide's estimate at the 0.05 level of significance? Perform a one-tailed

### Probability calculation based on Z score

34. Information from the American Institute of Insurance indicates the mean amount of life insurance per household in the United States is \$110,000. This distribution follows the normal distribution with a standard deviation of \$40,000. a. If we select a random sample of 50 households, what is the standard error of the mean?

### Calculating a Z Test for Proportion

A recent magazine article indicated that 47% of the general consumer population in the United States is loyal to the automobile manufacturer of their choice. Suppose Chevrolet did a study of a random sample of 1006 Chevrolet owners and found that 490 said that they would buy another Chevrolet. Does this indicate that the popul