Anew production process has been adopted for ub company that manufactures brushings. historical data suggest that these brushing diameter is normally distributed with a standard deviation of 1mm. it is believed that the modification has not affected the shape of the distribution or the standard deviation, but the value of the mean diameter may have changed. a sample of 25 housing units is selected and hole diameter is 6.45. (a) calculate a confidence interval for true average hole diameter using a confidence level of 90%. (b) a processor engineer believes that the confidence interval derived from (a) is too large for quality control. he/she wishes to derive a confidence interval at 90% confidence level that is smaller than 0.1mm. what should his/her sample size be? provide the smallest possible sample size to achieve 0.1mm confidence interval.

a. the are of the rectangle is 18.25

b. 18.25 times two is 36.50

rae me : d

introduction, methodology, results, discussion

step-by-step explanation:

an observational study is one which consists of actual observation to record data and then analyse the data.

there are a number of factors that should be analyzed before starting an observational study.

the main four factors are:

i) introduction:   this should be analysed to check whether the purpose of the study is correctly established and the data recorded are appropriate for the study

methodology:   the method of collecting the data, such as whether randomly selected, and whether sample size matches with the population to be studied, whether questions asked are easy to answer by common men, etc.

results: then results such as summary of data with comments should be studied thoroughly

discussion:   the last is the discussion, this can be either by management people or persons who are all interested , etc.

practice. practice. practice.