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# Tip #19 to Get a Top ACT Math Score (page 2)

By McGraw-Hill Professional
Updated on Sep 7, 2011

1. E To find perimeter, just add up the sides. To avoid a careless error and to make it clear what to do next, sketch a diagram. Since all sides of a square are equal, perimeter = 4(side) = 4(75) = 300.
2. J The volume of a rectangular solid, i.e., a box, equals (length)(width)(height). Just fill the info that we know into the formula, and solve for the variable that we are missing. This is a great word problem strategy. It solves 90% of all formula-related word problems. Just "fill in what we are given and solve for whatever is still a variable." So
3. D The area of a parallelogram = (base)(height). So
4. The key here is to memorize the parallelogram formula and to remember that 15 is the height, not 17. Height is always at a right angle, like when the nurse at school is measuring your height and says, "Stand up straight, no slouching." Also, remember to add the two parts of the base, 8 + 32 = 40.

5. K The word "circumscribed" throws some kids. Lot's of kids say, "I don't know that word, I'll just guess and move on." But in this book you'll learn all that you need for the ACT. When they throw a tough word at you that we have not discussed in this book, they'll define it in the question or you won't even need it. Here we don't need the word; you can cross it out. It's totally implicit in the diagram.
6. "Circumscribed" just means "drawn around." So the square is drawn around the circle, which is obvious from the diagram anyway! So, don't get intimidated. Stay confident and focused. So the area of the square = (length)(width). And for a square, length and width are equal. You can see in the figure that the circle has a radius of 9 and a diameter of 18, and you can see that the diameter is the same as the length of a side of the square, so its area = (18)(18) = 324.

7. C The ACT loves these. The key here is to realize that all the vertical lengths of the steps add up to 7, and all the horizontal lengths of the steps add up to 10. Now that you know this trick, it's easy! So perimeter = 34.

Go to: Tip #20