Question

An arborist would like to know if the mean growth (in inches) per year of flowering pear trees is different than white fir trees. A random sample of 37 flowering pear trees is taken, where the age of each tree is recorded. A white fir tree of the same age is located for a total of 37 white fir trees. The growth in height over a 1-year period for each tree in the study is carefully recorded. Summary statistics are given below.

Difference	n	Mean Diff	Std. Err.
d = Pear - Fir	37	-1.8	0.66

Can you conclude the mean yearly growth is different between flowering pear and white fir trees? Use a significance level of 0.01.

• Select the appropriate hypotheses to test the claim made.

  Ho:μd=0Ho:μd=0
  Ha:μd<0Ha:μd<0

  Ho:μd=0Ho:μd=0
  Ha:μd≠0Ha:μd≠0

  Ho:μd=0Ho:μd=0
  Ha:μd>0Ha:μd>0

• αα =    reject HoHo if probability ? < ≠ >   αα
• TS: t =    (Give answer to 3 digits after the decimal point.)
• probability = Select an answer 0.0098 0.9951 0.0049
• decision: Select an answer Reject H₀ fail to reject H₀
• At the 0.01 level, there Select an answer is not is  significant evidence to conclude the mean growth among flowering pear trees annually is different than the meam growth among white fir trees.

Answer 1

The statistical software output for this problem is:

On the basis of above output:

Hypotheses:

Ho:μd=0
Ha:μd≠0

α = 0.01

t = -2.727

Probability = 0.0098

Decision: Reject Ho

Conclusion: is significant evidence