You are asked to build some models of methane molecules for a science fair. You will arrange your model atoms as shown on the right, but you will use ping-pong balls and tennis balls to model hydrogen atoms and carbon atoms. If you have 12 ping-pong balls, how many tennis balls will you need? Use the model you just developed to justify your answer.

The research of robert siegler and eric jenkins on the development of the counting-on strategy is an example of design.

"jake’s roof repair has provided the following data concerning its costs: fixed cost per month cost per repair-hour wages and salaries $ 20,900 $ 15.00 parts and supplies $ 7.70 equipment depreciation $ 2,800 $ 0.35 truck operating expenses $ 5,720 $ 1.60 rent $ 4,690 administrative expenses $ 3,850 $ 0.50 for example, wages and salaries should be $20,900 plus $15.00 per repair-hour. the company expected to work 2,600 repair-hours in may, but actually worked 2,500 repair-hours. the company expects its sales to be $47.00 per repair-hour. required: compute the company’s activity variances for may."

Ray gives his son, mason, three bowls. these bowls have the same capacity, but each one differs slightly in its shape and size. ray tells his son that one of the bowls can hold more liters of oil than the other two bowls. mason points out that all the bowls, though may appear different in size and shape, can store the same volume of oil. in this case, ray was most likely testing mason's concept of