Question

A biologist would like to know information about the average height of all giraffes. He takes a sample of 9 giraffes and measures their heights (in feet):

17, 15, 19, 16.5, 18.1, 17.3, 16.8, 16.5, 19.

He would like to give a 99% confidence interval. Which test should he use?

The biologist can be 99& confident that the average height for all giraffes is between ______ & ______

What is the margin of error?

Answer 1

Answer)

First we need to fine the mean and standard deviation of the given data set

Mean = 17.24

S.d = 1.29

N = 9

As the population s.d is unknown here and we are given with sample s.d as the best estimate

We will use t distribution to estimate the interval

Degrees of freedom is = n-1 = 8

For 8 dof and 99% confidence level is 3.36

Margin of error (MOE) = t*s.d/√n = 3.36*1.29/√9 = 1.4428

Interval is given by

(Mean - MOE, Mean + MOE)

[15.7972, 18.6828].

You can be 99% confident that the population mean (μ) falls between 15.7972 and 18.6828.

answered by: anonymous