An online survey on a vegetable gardening website found that respondents who planted after April 1 had greater yields than those who planted before April 1. Describe why this survey is an
example of an observational study and not an experiment. Do you think there might be a bias? If
so, why?

Determine whether the following statements are true and give an explanation or counterexample. bold a. when using the shell method, the axis of the cylindrical shells is parallel to the axis of revolution. bold b. if a region is revolved about the y-axis, then the shell method must be used. bold c. if a region is revolved about the x-axis, then in principle it is possible to use the disk/washer method and integrate with respect to x or the shell method and integrate with respect to y.

The area of a rectangle is 54x^9y^8 square yards. if the length of the rectangle is 6x^3y^4 yards, which expression represents the width of the rectangle in yards

You are at a restaurant and owe $56.20 for your meal. you want to leave an 18% tip. approximately how much is your tip?