GGR270H1 Final: Week 6 Study Notes

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tealwhale232

13 Dec 2010

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Ggr 270 lecture 6 october 20, 2010. aim of inferential stats is to generalize about characteristics of larger population. so, need a process to obtain a sample. Therefore, an essential skill for any geographer to have. necessary is cases o extremely large populations. efficient and cost-effective way of understanding the population. highly detailed information can be obtained easily. If a sample is representative of the population then it will accurately reflect the characteristics of the population, without bias. element of randomness must be introduces to preserve the representative sample. can never eliminate bias, only minimize it. precision and accuracy help categorize sources of error. different number of sampling designs: www. notesolution. com: simple random, systematic sampling, stratified. can also have a series of spatial sampling designs: use cartesian coordinates, simple, stratified random, transect. sample statistics will change or vary for each random sample selected.

Related Questions

The fish population P(t) in a lake is suddenly attacked by adisease that render the fish unable to reproduce. Assuming that thedeath rate of the fish is inversely proportional to the square rootof the fish population (i.e. k1 = Î²/â(P) where Î² is aconstant), perform the following tasks:

1. Write a differential equation that models the population offish as a function of time. Assume that the fish are infected bythe disease at t = 0 and define your constants.

2. Solve the differential equation with the initial condition thatP(0) = P0.

3. What is the half-life of the fish population?

4. If there were 900 fish initially, and 441 are left after 6weeks, how long does it take for all the fish to die? Assume thatthe disease was caused by radioactive waste dumped in the lake. Itis discovered that another population of fish, S(t), spontaneouslymutate into the original fish at a rate of k2 (per week) and neverdie. The population S(t) are born at a rate k3.

5. Draw a diagram that describes the life cycle of these twofish populations including your rate constants.

6. Write the differential equations describing the populationsof P(t) and S(t).

George Smits owns George's Joint, a gas station and convenience store. George is trying to get a better understanding of his business and wants to estimate the mean number of gallons of gasoline sold to his customers. Assume the number of gallons of gasoline sold follows a normal distribution with a population standard deviation of 2.3 gallons. From these records, he randomly selects 60 sales and finds the mean number of gallons sold is 8.6

What is the point estimate of the population mean?

silverbeaver496

The average length of a roller coaster ride is 112 seconds with a known population standard deviation of 50.5 seconds. Suppose we take a sample of the last 100 roller coasters that were built and find that the average of those 100 is 105 seconds. We are interested in seeing if the actual average length of a roller coaster ride is significantly different than 112 seconds.

a. What is the standard error?

b. What is the margin of error at 90% confidence?

c. Using my sample of 100, what would be the 90% confidence interval for the population mean?

d. If I wanted to control my margin of error and set it to 5 at 90% confidence, what sample size would I need to take instead of the 100?

purplewhale646

GGR270H1 Final: Week 6 Study Notes

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