Margin of Error and Interpreting Confidence Intervals

1. Calculate backpack weight as a percentage of body weight by typing =b2/a2 in cell C2, pressing return, then dragging the formula to cell C11. 2. Calculate the mean and standard deviation of these percentages. (Use one variable analysis and show statistics).

3. Find the margin of error for the mean you calculated. To do this, use the formula .

4. What do the results of this study say about backpack weights?

1. The school newspaper at a large high school reported that 120 out of 200 randomly selected students favor assigned parking spaces. Compute the margin of error. Interpret the resulting interval in context.

2. A newspaper in a large city asked 500 women the following: “Do you use organic food products (such as milk, meats, vegetables, etc.)?” 280 women answered “yes.” Compute the margin of error. Interpret the resulting interval in context.