Statistics
posted by Dawn .
63.4 65.0 64.4 63.3 54.8 64.5 60.8 49.1 51.0
Assume that these observations are an SRS from the late Cretaceous atmosphere. What is the mean percent of nitrogen in ancient air with a 90% confidence level?
Hint: uses onesample t confidence

Formula: CI90 = mean + or  (tvalue)(sd/√n)
Determine the tvalue from a ttable. Use degrees of freedom 8 (which is sample size minus one). You will also need to determine the mean by adding up the values and dividing them by the sample size. Find sd (standard deviation) as well. Substitute those values into the formula to calculate the confidence interval.
I hope this will help get you started.
Respond to this Question
Similar Questions

Statistics
Biologists studying the healing of skin wounds measured the rate at which new cells closed a razor cut made in the skin of an anesthetized newt. Here are data from 18 newts, measured in micrometers per hour: 29,27,34,40,22,28,14,35,26,35,12,30,23,18,11,22,23,33. … 
statistics
Pleas HeLp!!!!!!!!!! A random sample of the test scores of 100 applicants for college entry at a large junior college showed a mean score of 72.6. Determine a 99%, 95%, and 90% confidence interval for the m mean score of all applicants … 
statistics
A 90% confidence interval for a population mean based on 144 observations is computed to be (2.7,3.4). How many observations must be made so that 90% confidence interval will specify the mean to within ± 0.2 
statistics
okay heres the question and the answer I have, but Im not sure its right because the values seem way too high to interpet what it means..: Data: 63.4,65.0,64.4,63.3,54.8,64.5,60.8,49.1,51.0 "Assume that these observations on SRS from … 
MathStatistics
Find a confidence interval for ƒÊ assuming that each sample is from a normal population. a. P x = 14, ƒÐ = 4, n = 5, 90 percent confidence b. P x = 37, ƒÐ = 5, n = 15, 99 percent confidence c. P x = 121, ƒÐ = 15, n = … 
Statistics
A 95% confidence interval for a population mean, ? 
Statistics
Problem 1 Use the Old Faithful data labelled Duration as a sample for problem 1. a. Determine the proportion of instances that the duration was less than 240 seconds. Also express the proportion as a percent. (hint: proportion is number … 
math
assume that a sample is used to estimate a population proportion p. find the margin of error E that corresponds to the given statistics and confidence level. 98% confidence, the sample size is 780, of which 40% are successes what does … 
Statistics
The standard deviation for a population is σ = 15.3. A sample of 36 observations selected from this population gave a mean equal to 74.8. a) Make a 90% confidence interval for μ b) Construct a 95% confidence interval for … 
Business statistics
3. Determine the tcritical value for a twosided confidence interval in each of the following situations. a. Confidence level = 95%, df = 15 b. Confidence level = 99%, n = 5. c. Confidence level = 95%, n = 15 d. Significance level …