Negation, Kmart Barbells

If the statement “All sets of barbells in Kmart are on sale” is false, then which of the following statements must be true?

  1. All sets of barbells in Kmart are not on sale.
  2. There is some set of barbells in Kmart that is not on sale.
  3. No set of barbells in Kmart is on sale.
  4. Not all sets of barbells in Kmart are on sale.
  1. II only
  2. IV only
  3. I and III only
  4. II and IV only
  5. I, II, and IV only

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Wind Farm

Denmark is a major manufacturer of energy-producing wind turbines. Suppose both the following statements are true:

1. Some wind turbines in Ohio are not from Denmark, but are American-built.
2. All of the wind turbines in Lorain County are indeed from Denmark.

From these two statements, which of the following can be concluded?

  1. Some American-built wind turbines are in Lorain County.
  2. All Lorain county wind turbines are not American-built.
  3. Some American-built wind turbines are not in Lorain County.
  4. No Lorain County wind turbine is American-built.
  5. Some wind turbines in Ohio, but not in Lorain County, were built in Denmark.

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Volume of a Shell and Solid

Imagine a rectangular solid that is made up of smaller unit cubes. The solid measures x by y by z. Now imagine building a shell of unit cubes around the entire solid.

First question: what is an equation for the number of unit cubes in the shell, in terms of x, y, and z?

Second question: for what x, y, and z is the number of cubes in the rectangular solid equal to the number of cubes in the shell?

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Water Poured Into Liter Cube

Water is poured at a constant rate into a one-liter cube near its corner. The water rises to the halfway mark, stops for a moment, and then continues to rise at exactly half its previous rate. The reason is that inside the cube is a hollow cylindrical can that has been attached to the bottom. What are the height and radius of the can? (Recall that a one-liter cube measures 10 cm on each edge.)

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