Question

Great white sharks are big and hungry. Here are the lengths in feet of 44 great whites.

18.7 16.6 13.2 18.9

12.2 16.5 16.0 16.2

18.6 17.7 14.1 22.7

16.4 16.0 16.8 16.6

15.7 12.8 9.3 13.5

18.2 17.8 18.1 13.0

14.7 13.6 13.2 15.7

15.8 12.4 13.6 19.7

14.7 15.2 15.2 18.7

17.5 14.6 16.1 13.1

12.3 12.6 13.6 16.8

Follow the JMP steps below for this question.

1. Open JMP, click File > New > Data Table . This will open a new data table with one column named Column 1. Double-click at the variable name Column 1 and rename it to Length.
2. Move the cursor to highlight and copy these data. Next, at the JMP table, point and click at the first row under the variable and paste data values into this column.
3. Click Analyze > Distribution , select Length for Y, Columns and click OK
4. On the output window, click the red triangle besides the variable Length and select Normal Quantile Plot.
5. Read the Summary of Statistics (no calculation needed) at the output window to find answers for parts (a), (b), and (c) .

Examine these data for shape, center, spread and outliers. The normal quantile plot indicates the distribution is reasonably Normal except for one outlier in each direction. Because these are not extreme and preserve the symmetry of the distribution, use of the t procedures is safe with 44 observations.

(a) Find the sample mean and sample standard deviation.

x	=  ft (Round to 2 decimal places.)
s	=  ft (Round to 3 decimal places.)

(b) The standard error of sample mean is
SE(x) =  ft. (Round to 3 decimal places.)

(c) Use these data to give a 95% confidence interval for the mean length of all great white sharks.
to  ft (Round to 2 decimal places.)

Answer 1

the quantile plot is

since the data stat>basic stat>one sample t

we have

One-Sample T: data

Variable N Mean StDev SE Mean 95% CI
data 44 15.561 2.528 0.381 (14.793, 16.330)

(a)the sample mean and sample standard deviation.

sample mean = 15.56

sample standard deviation = 2.528

(b) The standard error of sample mean is
SE(x) =0.381
(c) 95% confidence interval for the mean length of all great white sharks.

14.79 to  16.33