The following are tensile strengths of cotton fibers from two suppliers of a tex

Question

The following are tensile strengths of cotton fibers from two suppliers of a textile mill.

(a) Use StatKey to create a bootstrap distribution (consisting of at least 5000 bootstrap samples) based on the sample data. Copy screenshots of the bootstrap dotplot and original sample box into your assignment.

Supplier A 78 82 85 83 77 74

Supplier B 76 79 83 78 72 73 81

(b) Find a 95% confidence interval for the difference between the average tensile strength of Supplier A’s cotton and the average tensile strength of Supplier B’s cotton.

(c) Is it reasonable to conclude that there is a difference in average tensile strength between Supplier A’s cotton and Supplier B’s cotton? Why or why not?

d) Now, suppose another measurement was taken from Supplier A, and that measurement is a tensile strength of 10. Construct another bootstrap distribution with the seventh Supplier A measurement included. Then fill in the blanks in the following statement. The possible answers are included underneath the statement.The shape of the bootstrap distribution is ______________________ , and the distribution has ______________________ , so it ___________ appropriate to use the methods of Chapter 3 to find a bootstrap confidence interval.

Explanation / Answer

a)

b)

95% confidence interval for the difference in means

-1.774, 6.702

c)

CI = diff in mean +/- t0.025 * std error

(-2.6109,7.4203)

c)

since p-value is not less than 0.05, donot reject null hyptothesis. there is no significant difference between means.

d)

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