Education.com
Try
Brainzy
Try
Plus

# Confidence Intervals and Tests of Hypotheses for Means Practice Questions

(not rated)
By
Updated on Oct 5, 2011

To review these concepts, go to Confidence Intervals and Tests of Hypotheses for Means Study Guide.

## Confidence Intervals and Tests of Hypotheses for Means Practice Questions

### Practice

1. A study was conducted to determine the mean birth weight of a certain breed of kittens. The birth weights of kittens are normally distributed. A sample of 43 kittens was randomly selected from all kittens of this breed born at a large veterinary hospital. The birth weight of each kitten in the sample was recorded. The sample mean was 3.47 ounces, and the sample standard deviation was 0.1 ounces. Set a 95% confidence interval on the mean birth weight of all kittens of this breed. Interpret the interval in the context of the problem.
2. A random sample of 50 lakes was selected from all lakes in a state. The average nitrogen level of these lakes was 754 μg/l, and the sample standard deviation was 18 754 μg/l. Set a 90% confidence interval on the mean nitrogen level of the lakes in this state.
3. Consider again the sample of 50 lakes mentioned earlier in practice problem 2. The state has a large farm economy. A politician has promoted laws that will encourage farmers to adopt practices that will minimize the amount of nitrogen entering the lakes. He has declared that this program has been successful because the mean nitrogen level in the state's lakes does not exceed 750 μg/l. The opposition party would like to say that his claim is not right and that the mean nitrogen level in the state's lakes exceeds 750 μg/l. Recall the average nitrogen level of the 50 sampled lakes was 754 μg/l, and the sample standard deviation was 18μg/l. Is there evidence that the politician is making a false claim?

#### Solutions

1. (3.44,3.50)
2. We are 90% confident that the mean nitrogen level of lakes in this state is within 4.2 μg/L of 754 μg/L within the study region.
Add your own comment

### Ask a Question

Have questions about this article or topic? Ask
150 Characters allowed

### Related Questions

#### Q:

See More Questions

### Today on Education.com

Top Worksheet Slideshows