# IM3.7B.3 Exit Ticket

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. Remember, this is a sample mean, so we use the formula .
3. What do the results of this study say about backpack weights?

## MOE-Proportion

These problems involve population **proportions** so remember to use the formula:
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.