Question

1. Zoo officials are interested in determining the predicted weight of newborn giraffes. A random sample of 8 newborn giraffes’ weights were obtained. Assume that newborn giraffes’ weights are Normally distributed. From the sample, the mean weight was 137 lbs and the standard deviation was 12.5 lbs. Construct and interpret a 99% confidence interval for the population mean weight of all newborn giraffes.

2. Students in one sample were shown positive evaluations of an instructor and the students in a second sample were shown negative evaluations of an instructor. Then, all subjects were shown the same lecture video given by the same instructor. They were then asked to rate the instructor using three questions and a summary rating was calculated. Is there evidence that the students’ rating was influenced by the prior student evaluations? Perform a hypothesis test with a 5% level of significance to determine if students gave the instructor a higher score if they were shown positive evaluations versus negative evaluations. Assume that both samples come from Normally distributed populations.

	Positive (1)	Negative (2)
xi	2.613	2.236
si	0.533	0.543
ni	25	24

df=46

steps:

i.

ii.

iii.

Answer 1

( 1 )

99% confidence interval for the population mean is  (121.534,152.466)

Note : In problem ( 2 ) recheck the data sample size and degrees of freedom