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30 Insulators Level of Significance: Evaluating Force

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An organization thinks that if the electrical insulators break when in use, a short circuit might occur. To test the strength of the insulators, a hard core test will be performed to determine how much force is required to break the insulators. Force is measured by observing the number of pounds of force (lbs.) applied to the insulators before it has a chance to break. The data from 30 insulators subjected to this testing is tabulated below (please refer to attached file to view the chart for this question).

Questions:
a. At the 0.05 level of significance, is there evidence that the population mean force is greater than 1,500 lbs.?
b. What assumption about the population distribution is needed in order to conduct the t test in (a)?
c. Construct a histogram and boxplot to evaluate the assumption made in (b).
d. Do you think that the assumption needed in order to conduct t test in (a) is valid? Explain.

https://brainmass.com/statistics/hypothesis-testing/insulators-level-significance-evaluating-force-502538

Solution Preview

a) The mean µ=1723.4, standard deviation s=89.5508.
Null hypothesis: µ<=1500
Alternative hypothesis: µ>1500
This is a one tailed t test and the degree of freedom ...

Solution Summary

The expert examines 30 insulators level of significance for evaluating forces. The assumptions about the population distribution is needed in order to conduct the t test in (a) are provided.

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Statistics for Managers

A manufacturing company produces electrical insulators. If the insulator breaks when in use, a shor circuit is likely to occur. To test the strength of the insulators, destructive testing is carried out to determine how much force is required to break the insulators. Force is measured by observing the number of pounds of force applied to the insulator before it breaks. The following data (stored in force) are for 30 insulators subjected to this testing.
1,870 1,728 1,656 1,610 1,634 1,784 1,522 1,696 1,592 1,662
1,866 1,764 1,734 1,662 1,734 1,774 1,550 1,756 1,762 1,866
1,820 1,744 1,788 1,688 1,810 1,752 1,680 1,810 1,652 1,736

a) At the 0.05 level of significance, is there evidence that the population mean force is greater than 1,500 pounds?

b) What assumption about the population distribution is needed in order to conduct the t test in (a)?

c) Construct a histogram, box plot, or normal probability plot to evaluate the assumption made in (b).

d) Do you think that the assumption needed in order to conduct the t test in (a) is valid? Explain.

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