In an automotive safety test conducted by the North Carolina Highway Safety Research Center, the average tire pressure in a sample of 62 tires was found to be 24 pounds per square inch, and the standard deviation was 2.1 pounds per square inch.
a) Calculate the estimated population standard deviation for this population. (There are about a million cars registered in North Carolina)
b) Calculate the estimated standard error of the mean.
c) Construct a 95 percent confidence interval for the population mean.
唔識做呢條數... 麻煩高手請進!~thanks!!!(2)
2009-06-05 10:22 am
回答 (2)
2009-06-05 9:29 pm
✔ 最佳答案
a) If 2.1 is the sample standard deviation, it would be an unbiased expected population standard deviation
b)
standard error = 2.1 / sqrt(62) = 0.2667
c)
by Central Limit Theorm, the tire pressure follows a normal distribution
95% confidence intervals:
24 - 1.96 x 2.1 / sqrt(62) < population mean < 24 + 1.96 x 2.1 / sqrt(62)
23.4773 < population mean < 24.5227
2009-06-05 13:58:21 補充：
eag583 is late by 24 seconds
Poor!
2009-06-05 9:53 pm
a)
If 2.1 is the sample standard deviation, it would be an unbiased expected population standard deviation
b)
standard error = 2.1 / sqrt(62) = 0.2667
c)
by Central Limit Theorm, the tire pressure follows a normal distribution
95% confidence intervals:
24 - 1.96 x 2.1 / sqrt(62) < population mean < 24 + 1.96 x 2.1 / sqrt(62)
23.4773 < population mean
g
If 2.1 is the sample standard deviation, it would be an unbiased expected population standard deviation
b)
standard error = 2.1 / sqrt(62) = 0.2667
c)
by Central Limit Theorm, the tire pressure follows a normal distribution
95% confidence intervals:
24 - 1.96 x 2.1 / sqrt(62) < population mean < 24 + 1.96 x 2.1 / sqrt(62)
23.4773 < population mean
g
參考: .yahoo.com
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