Investment Returns:These data are the annual returns on shareholders’ funds of 97 of Australian’s top 100 companies for the years 1990 and 1998.

(i)Produce a histogram of the 1990 returns.

(ii)Produce a histogram of the 1998 returns.

(iii)Find the mean, median, range and standard deviation for the 1990 returns. Annual Returns % (1990)
Mean12.91865979
Median11.38
Standard Deviation9.297513067
Range75.01

(iv)Repeat part (iii) for the 1998 returns.
Annual Returns % (1998)
Mean6.355463918
Median5.4
Standard Deviation5.170830853
Range42.76

(v)Which was the better year for investors?
•1990 was the better year for investors in regards to annual returns being consistent with the mean of 12.9% compare to 6.4% for 1998. •The measure of variability was high in 1990 with the range of 75.01 compare to 42.76 for 1998. Another high variability for 1990 was the standard deviation of 9.30 compare to 5.17 for 1998.

(For Excel instructions see pages 28 and 61 of the textbook.)

Question 2.(Statistical Inferences: Single Population)

Feasibility Study: Companies that sell groceries over the Internet are called e-grocers. Customers enter their orders, pay by credit card and receive delivery by truck. To determine whether an e-grocery would be profitable in one large city, a potential e-grocer offered the service and recorded the size of the order for a random sample of customers. The data are stored in the data file.

(i)Estimate with 95% confidence the average order in the city. Orders ($)
Mean89.16511905
Confidence Level (95.0%)3.770623926

(ii)Financial analysis indicates that to be profitable the average order would have to exceed $85. Can we infer from the data that an e-grocery will be profitable in the city? Test using = 0.01.

Step 1: Hypothesis is that to be profitable the average order has to exceed $85. Since it’s unproven, it is the alternative hypothesis. The null...

...Inferences for One Population StandardDeviation
The Standarddeviation is a measure of the variation (or spread) of a data set. For a variable x, the standarddeviation of all possible observations for the entire population is called the population standarddeviation or standarddeviation of the variable x. It is denoted σx or, when no...

...temperature of baboons = 98.6°.
Ho: μ = 98.6° It is a two-tailed test.
Ha: μ ≠98.6°
c) The majority of the American adults support Healthcare reform.
Ho: p ≤ 50% It is right tailed
Ha: μ > 50%
d) The standarddeviation for human body temperatures is less than 0.02°
Ho: σ ≥ 0.02° It is left tailed
Ha: σ < 0.02°
7. Claim: The mean test score on a given test is greater than 165 points.
Sample...

...Chapter 10
StatisticalInferences Based on Two Samples
True/False
1. An independent sample experiment is an experiment in which there is no relationship between the measurements in the different samples.
Answer: True Difficulty: Medium
2. When testing the difference between two proportions selected from populations with large independent samples, the Z test statistic is used.
Answer: True Difficulty: Medium
3. In forming a large sample...

...the actuarial field and finds the average salary to be $41,000. The population standarddeviation is $3000. Can her claim be supported at 0.05?
x¯=14.7, μx¯=13.77, ox¯=5.34, n=29, α=.01
3. Monthly Home Rent. The average monthly rent for a one bedroom in San Francisco is $ 1229. A random sample of 15 one bedroom homes about 15 miles outside of San Francisco had a mean rent of $1350. The population standarddeviation is $250. At...

...Standarddeviation can be difficult to interpret as a single number on its own. Basically, a small standarddeviation means that the values in a statistical data set are close to the mean of the data set, on average, and a large standarddeviation means that the values in the data set are farther away from the mean, on average.
The standarddeviation measures how...

...Deviation
Definition:
Behavior commonly seen in children that is the result of some obstacle to normal development such behavior may be commonly understand as negative (a timid child, a destructive child) or positive (a quite child), both positive and negative deviation will disappear once the child begins to concentrate on a piece of work freely chosen by him.
The physical deforms are easier to identify. This can be by birth due to an accident...

...I'll be honest. Standarddeviation is a more difficult concept than the others we've covered. And unless you are writing for a specialized, professional audience, you'll probably never use the words "standarddeviation" in a story. But that doesn't mean you should ignore this concept.
The standarddeviation is kind of the "mean of the mean," and often can help you find the story behind the data. To...

...StandardDeviation (continued)
L.O.: To find the mean and standarddeviation from a frequency table.
The formula for the standarddeviation of a set of data is [pic]
Recap question
A sample of 60 matchboxes gave the following results for the variable x (the number of matches in a box):
[pic].
Calculate the mean and standarddeviation for x....

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