Question

researcher wishes to test the claim that the average weight of an adult elephant is 12500 pounds. The researcher collected a sample of 33 adult elephants. The sample average for the weight of the elephants was 12200 pounds. The population standard deviation is believed to be 720 pounds. With alpha = 0.06, is there enough evidence to reject the claim.

a) Is this a test that uses, z-scores, t-scores, or chi-squared values?

b) [2 points] Does this problem involve proportions?

c) What is(are) the critical value(s) for the problem?

d)What are the test values and which formula did you use?

e) Should the researcher reject the claim?

Answer 1

a)

H0: = 12500

Ha 12500

Since population standard deviation is known, this test uses z-score.

b)

Does not involve proportions

c)

From Z table,

Critical values at 0.06 level are -1.881 , 1.881

d)

Test statistics

z = ( - ) / ( / sqrt(n) )

= ( 12200 - 12500) / (720 / sqrt(33) )

= -2.39

e)

Since test statistics < -1.88 , Reject the null hypothesis.

We conclude that we have sufficient evidence to reject the claim.