1. For a standard normal distribution, determine that probability that z is between 2.2 and 2.55; that is, find P(2.2 < z <55).

2. Before any order is shipped, inspectors at UPS 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?

Group of answer choices

none of these

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.

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

Approximately 95% of the units in the order will have a breaking strength of between 806.5 lbs. and 821.5 lbs.

3. You take all possible samples of size 100 from a very large population of values. The mean of the population is 550. The standard deviation is 50. You compute the mean of each sample. 95% of the sample means will be greater than _________.