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hussainizzle hussainizzle
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3 weeks ago
Use the following to answer the questions below:

A certain species of tree has an average life span of 130 years. A researcher has noticed a large number of trees of this species washing up along a beach as driftwood. She takes core samples from 27 of those trees, selected at random, to count the number of rings and measure the widths of the rings. Counting the rings allows the researcher to determine the age of each tree. The mean age of the sampled driftwood is 119 years old, with standard deviation 46.92 years. The sample data are plotted in the provided dotplot. One of her interests is determining if this sample provides evidence that the average age of the driftwood is less than the 130 year life span expected for this type of tree. If the average age is less than 130 years it might suggest that the trees have died from unusual causes, such as invasive beetles or logging.
A dotplot depicts the results of the average life span for certain species of tree. The horizontal axis is labeled Age and has markings from 50 to 200 in increments of 25. The dots are plotted as follows: 1 dot above 50; 3 dots above 60; 1 dot above 65, 70, and 75; 2 dots above 80, and 100; 1 dot above 105, 115, and 120; 2 dots above 125; 1 dot above 130, 135, 145, and 150; 2 dots above 160; 1 dot above 165; and 2 dots above 190, and 200. There is no dot above 175. All values are approximate.

Test, at the 5% level, if there is evidence that the average age of driftwood along this beach is significantly below 130 years. Include all of the details of the test.
Textbook 
Statistics: Unlocking the Power of Data

Statistics: Unlocking the Power of Data


Edition: 3rd
Authors:
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localbabe10localbabe10
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hussainizzle Author
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