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Death Rolls. Alligators perform a spinning maneuver, referred to as a "death roll," to subdue their prey, Videos were taken of juvenile alligators performing this maneuver in a study for the article "Death Roll of the Alligator, Mechanics of Twist and Feeding in Water" (Journal of Experimental Biology, Vol. 210,pp.2811-2818)by F. Fish et al. One of the variables measured was the degree of the angle between the body and head of the alligator while performing the roll. A sample of 20rolls yielded the following data, in degrees.

58.658.757.354.552.9
59.529.443.431.852.3
42.734.839.261.360.4
51.542.857.543.647.6

At the 5%significance level, do the data provide sufficient evidence to conclude that, on average, the angle between the body and head of an alligator during a death roll is greater than 45?

(Note: x=49.0and s=10.0)

Short Answer

Expert verified

The significance level is, =0.05

The MINITAB Output P-value is 0.045

Step by step solution

01

Given Information,

Check whether the data provide sufficient evidence to conclude that on average the angle between the body and head of an alligator during a death roll is greater than 45

State the null and alternative hypothesis:

Null Hypothesis:

H0:=45

That is, the data does not provide sufficient evidence to conclude that on average the angle between the body and head of an alligator during a death roll is greater than 45

Alternative Hypothesis:

Ha:>45

That is, the data provide sufficient evidence to conclude that on average the angle between the body and head of an alligator during a death roll is greater than 45

Decide a significance level

Here, the significance level is, =0.05

02

Definition,

Compute the value of test statistic and P value using MINITAB

MINITAB procedure:

Step 1: Choose Stat > Basic Statistics > 1-Sample t.

Step 2: In Summarized data, enter the sample size 20 and mean 49 .

Step 3: In Standard deviation, enter a value 10 .

Step 4: InPerform hypothesis test, enter the test mean as 45.

Step 5: Check Options, enter Confidence levelas 95 .

Step 6: Choose greater thanin alternative.

Step 7: Click OK in all dialogue boxes.

MINITAB output:

One-Sample T

Test of mu = 45 vs >45





95% lower

NMeanStDevSE MeanBoundTP
2049.0010.002.2445.131.790.045

From the MINITAB Output the value of test statistic is localid="1651581810106" 1.79

From the MINITB Output, The P-value is localid="1651581819598" 0.045

03

Expression,

Conclusion

If P, then reject the null hypothesis.

Here the P-Value is 0.045 which is less than the level of significance. That is,

P=0.045<=0.05

Therefore, the null hypothesis is rejected at 5%level.

Thus, it can be conclude that the test results are statistically significant at 5%level of significance.

Interpretation:

Thus, the data provide sufficient evidence to conclude that on average the angle between the body and head of an alligator during a death roll is greater than 45.

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