# Assumptions, Calculations, and Confidence Interval for Means

Your manager is asking for the average viscosity of a product that you produce in a batch process. Recorded below are the 12 most recent values, taken from consecutive batches. State any assumptions, and clearly show the calculations that are required to estimate a 95% confidence interval for the mean. Interpret that confidence interval for your manager, who is not sure what a confidence interval is.

Raw data: [13.7, 14.9, 15.7, 16.1, 14.7, 15.2, 13.9, 13.9, 15.0, 13.0, 16.7, 13.2]

Mean: 14.67

Standard deviation: 1.16

https://brainmass.com/statistics/descriptive-statistics/assumptions-calculations-confidence-interval-means-598675

#### Solution Preview

First, we need to tell manager that the confidence interval is used the measure the accuracy of mean.

To calculate a 95% confidence interval, the following assumptions must be met:

1. The data for 12 batches must be a simple random sample from a population

2. The data for 12 batches must be independent of each other

3. The data for 12 batches must be drawn from a population which has a ...

#### Solution Summary

The solution gives detailed steps on stating assumptions, showing calculations, and interpreting the confidence interval for means.