Before any order is shipped, inspectors at Alvarez Manufacturing test a sample of finished units for breaking strength.You select a simple random sample of units from a recently completed order and find that the sample average breaking strength is 814 pounds.From the sample selected, you construct a 95% confidence interval estimate of the average breaking strength you could expect to find if all the units in the order were tested.The interval turns out to be 814 ± 7.5 lbs.How would you interpret your result?
A)Approximately 95% of the units in the order will have a breaking strength of between 806.5 lbs.and 821.5 lbs.
B)Approximately 95% of the units in the sample have a breaking strength of between 806.5 lbs.and 821.5 lbs.
C)Approximately 95% of the units in the population will have a breaking strength of between 806.5 and 821.5 lbs.
D)We can be 95% confident that all the units in the order have a breaking strength of between 806.5 lbs.and 821.5 lbs.
E)If we were to repeat this estimating procedure a large number of times, approximately 95% of the intervals we construct would contain the actual order average breaking strength.

Question

Quizplus · Accepted Answer

The correct interpretation of a confidence interval is that if we were to repeat the sampling and interval construction process many times, about 95% of those intervals would contain the true population mean. This statement does not imply that a specific percentage of individual units fall within the interval, nor does it guarantee the exact range of breaking strengths for all units.

Before Any Order Is Shipped, Inspectors at Alvarez Manufacturing Test