Confidence Intervals

Tuesday September 18, 2007 by Donald Hennenfent

We are conducting a survey which will provide us with
1 an estimate of the number of companies using a given product
2. The average annual consumption of that product

Each of these estimates will have a confidence interval around it
and I know how to calculate these.

Multiplying the number of companies using the product times the average annual consumption will give me an estimate of the "Total consumption". My question is how do calc a confidence interval around that estimate, give that it is composed of two seperate set of confidence intervals. Any help, greatly appreciated.

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