Suppose that a travel bureau claims that the trees in a forest are 85 feet tall
on average, with a standard deviation of 2 feet. If you took a sample of 64
trees, which of the following mean heights would be outside the 95%
confidence interval?
O A. 84.4 feet
B. 84.6 feet
C. 85.2 feet
D. 84.8 feet

Respuesta :

Answer

A. 84.4

Step-by-step explanation:

The heights would be outside the 95% confidence interval will be 84.6 feet. Then the correct option is B.

How to calculate confidence interval for population mean for small sample?

If the sample size is given to be n < 30, then for finding the confidence interval for mean of population from this small sample, we use t-statistic.

Let the sample mean given as μ and

The sample standard deviation σ, and

The sample size = n, and

Suppose that a travel bureau claims that the trees in a forest are 85 feet tall on average, with a standard deviation of 2 feet.

If you took a sample of 64 trees.

Then the heights would be outside the 95% confidence interval will be

For 95% confidence interval, we have z = 1.645

⇒ μ ± z (σ/√n)

⇒ 85 ± 1.645 (2/√64)

For negative sign, we have

⇒ 84.588

⇒ 84.6 feet

For negative sign, we have

⇒ 85.41

⇒ 85.4 feet

Then the correct option is B.

Learn more about confidence interval of population for small sample here:

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