Question

1.

Researchers at UT Austin noticed that the seagrass beds in Corpus Cristi Bay (CCB) were taller and thicker than those in Lower Laguna Madre (LLM). They compared the sediment ammonium concentrations in the two locations. Following are the summary statistics on sediment ammonium concentration, in micromoles, obtained by the researchers. Perform the required hypothesis test at the 1% significance level. Equality of variances is not assumed.

CCB: mean = 115.1, standard deviation = 79.4, n = 51

LLM: mean = 24.3, standard deviation = 10.5, n = 19

FIND T

t = ?

2.

Using data from Question 1, determine a 98% confidence interval for the difference between the mean sediment ammonium concentrations in CCB and LLM.

CCB: mean = 115.1, standard deviation = 79.4, n = 51

LLM: mean = 24.3, standard deviation = 10.5, n = 19

98% Confidence Interval = ?:  

3.

Can we use Z to obtain our critical value? Why or why not?

• A. We can use Z to obtain our critical value because the degrees of freedom are greater than 30.
• B. We cannot use Z to obtain our critical value because the degrees of freedom are less than 30.
• C. We cannot use Z to obtain our critical value because the degrees of freedom are greater than 30.
• D. We can use Z to obtain our critical value because the degrees of freedom are less than 30.

4. At the 1% significance level, is there sufficient evidence to conclude that the mean sediment ammonium concentration in CCB exceeds that in LLM?

• A. At the 1% significance level, there is evidence to conclude that the mean sediment ammonium concentration in CCB exceeds that in LLM because our t-value is greater than our critical value.
• B. At the 1% significance level, there is insufficient evidence to conclude that the mean sediment ammonium concentration in CCB exceeds that in LLM because our t-value is less than our critical value.
• C. At the 1% significance level, there is evidence to conclude that the mean sediment ammonium concentration in CCB exceeds that in LLM because our t-value is less than our critical value.
• D. At the 1% significance level, there is insufficient evidence to conclude that the mean sediment ammonium concentration in CCB exceeds that in LLM because our t-value is greater than our critical value.

Answer 1