The method of tree ring dating gave the following years A.D. for an archaeological excavation site. Assume that the population of x values has an approximately normal distribution.
1229 | 1320 | 1187 | 1243 | 1268 | 1316 | 1275 | 1317 | 1275 |
(a) Use a calculator with mean and standard deviation keys to find the sample mean year x and sample standard deviation s. (Round your answers to the nearest whole number.)
x = | A.D. |
s = | yr |
(b) Find a 90% confidence interval for the mean of all tree ring
dates from this archaeological site. (Round your answers to the
nearest whole number.)
lower limit | A.D. |
upper limit | A.D. |
From the given sample,
a)
= 1270
S = 45
b)
t critical value at 0.10 significance level with 8 df = 1.860
90% confidence interval for is
- t * S / sqrt(n) < < + t * S / sqrt(n)
1270 - 1.860 * 45 / sqrt(9) < < 1270 + 1.860 * 45 / sqrt(9)
1242 < < 1298
Lower limit = 1242
Upper limit = 1298
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