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The weights of a grapefruit follow a normal distribution. A random sample of 12 new hybrid grapfruit has a mean weight of 1.7 lb w/sample standard deviation of .24 lb. Find a 95% confidence interval for the population mean weight of hybrid grapefruit.

2007-07-24 06:49:46 · 2 answers · asked by Anonymous in Science & Mathematics Mathematics

2 answers

n = 12, so we must use the t tables with dof = 11
The critical t value for the 95% CI is 2.201

CI = xbar +/- tcrit*s/sqrt(n)
= 1.7 +/- 2.201*0.24/sqrt(12)
= 1.7 +/- 0.15
= [1.55, 1.85]

2007-07-24 06:54:28 · answer #1 · answered by Dr D 7 · 1 0

1.495 - 1.927

2007-07-24 13:56:48 · answer #2 · answered by gebobs 6 · 0 0

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