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# Confidence Interval for difference between proportions

To determine the possible effect of a chemical treatment on the rate of seed germination, 300 chemically treated seeds and 250 untreated seeds were sown. It was found that 267 of the chemically treated seeds and 205 of the untreated seeds germinated. Let P1 be the proportion of the population of all chemically treated seeds that germinate, and let P2 be the proportion of the population of all untreated seeds that germinate. Find a 90% confidence interval for P1-P2. Then complete the table below.

Answer to the 3rd Decimal

1. What is the lower limit of the 90% confidence interval?

2. What is the upper level of the 90% confidence interval?

#### Solution Preview

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To determine the possible effect of a chemical treatment on the rate of seed germination, 300 chemically treated seeds and 250 untreated seeds were sown. It was found that 267 of the chemically treated seeds and 205 of the untreated seeds germinated. Let P1 be the proportion of the population of all chemically treated seeds that germinate, and let P2 be the proportion of the population of all untreated seeds that germinate. Find a 90% confidence interval for P1-P2. Then complete the table below.

Answer to the 3rd Decimal

Data
Confidence level= 90%
Significance level=100%-Confidence ...

#### Solution Summary

Calculates the Confidence Interval for difference between proportions.

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