SECTION 4 1. B This simple equation should present you with little difficulty, but beware: It is on precisely such questions that your guard might come down and you can become careless! Using Plugging In The Answers is safest. Only B works: 2 + (0) = 2 – (0) 2=2 2. B As the directions at the beginning of every math section remind us, the area of a triangle is given by this formula: A = area is 2. A = bh. If the base is 4 and the height is 1, the × 4 × 1 = 2. 3. E If the area of square A is 16, the length of each side is 4, and the perimeter is 16. You are told that this is of B’s perimeter, which you can calculate: www.cracksat.net Now that you know the perimeter of B, you can calculate the perimeter of C: If the perimeter of C is 36, each side is 9, and the area of C is 92, or 81. If you chose B, you need to read the question more carefully. 4. E According to the ratios given, you know that the mixture contains more wheat than rye; there must be more than 5 pounds of wheat. So let’s eliminate A and B. Use the Ratio Box. Because there is a total of 5 pounds of rye, the multiplier is 2.5. This allows you to solve for 12.5 pounds for the wheat. 5. C Because 135° is one of the middle angles of the circle, the triangles must each have a 45° angle, and are therefore both identical 45°-45°-90° triangles. Remember (or www.satpanda.com check the front page of the test) that the ratio of the sides in such a triangle is x:x: x. You know that the diameter of the circle is 12, so the hypotenuse (which is equal to the radius of the circle) of each triangle is 6. If 6 is the long side, the other side of each triangle must be . Now you can find the area of one of the triangles and double it. The area of a triangle is . So bh, and both the base and height are equal to = 9. You have found the area for one of the triangles, so double it to get 18, or C. Another way to solve this is to use the side of your answer sheet as a ruler and ballpark. If XZ = 12, the hypotenuse of each triangle is 6. Now mark off the length of 6 with your homemade ruler and compare that to a side of one of the triangles. You can guesstimate that the side is about 4. Using that approximation, calculate that since the base and height of both triangles is 4, the area of each triangle is × 4 × 4 = 8. The area of both triangles together is 16, which is closest to 18, or C. ETS wants you to do complicated geometry, but all you care about is finding the answer. 6. A Translate each statement, piece by piece. The first part tells us that “ the product of x and y is 76.” Since product means multiplication, then the first equation must be xy = 76, so you can eliminate answers C and D. The second part says that “x is twice the square of y,” which translates to x = 2y2, so eliminate answers B and E, and A is the only answer left. Notice that only the y needs to be squared, which is why B is wrong. The second equation for B would be written as “the square of twice y,” which is not what the problem stated. www.cracksat.net 7. A Try roughly plotting the data points, and then look at your graph. Find the answer that best fits your graph. Alternatively, notice that the number of customers increases as the temperature increases. The line of best fit will go up as you follow the graph from left to right, so eliminate B, D, and E. Notice that the number of customers does not increase by the same number for each 10-degree temperature increase. This is an exponential increase, not a linear increase. So, the graph will be curved. Eliminate C. Only A fits the data in the chart. 8. E Plug in 6 for c. The question is now asking what percent of 18 is 9. The answer would be 50. Which-ever choice gives you 50 when 6 is plugged in for C is the answer. Therefore, E is the answer. Remember: Plugging in good numbers will make your life much easier! 9. D Draw the missing figures. When you sketch this out, you’ll see that it’s a right triangle with legs of lengths 4 and 5. Use the Pythagorean theorem: 42 + 52 = c2. Now solve for c. c2 = 41 and c = . Remember that the question asked for perimeter, so add up the sides: 4 + 5 + =9+ , which is choice D. www.satpanda.com 10. B If 20% of the coins are either nickels or dimes, 80% are neither. 80% of 220 equals 176. Use your calculator or write it out and solve: 11. D Take out your calculator: 216,000 + 20% of 216,000 = 259,200 204,000 + 20% of 204,000 = 244,800 259,200 – 244,800 = 14,400 Another route to the answer is to take the difference immediately (216,000 – 204,000 = 12,000) and then increase that by 20%. Watch out for partial answers. E is 20% of Springfield’s population, and A is the difference between 20% of Springfield’s population and 20% of Rockville’s population. 12. E With algebraic answer choices, you should plug in numbers. Let’s let x = y = 2, which makes z = 4. Plugging these values into the choices, you’d get the following: (A) 2(2) + 2(2) = 2(4) [Yes] (B) 2 – 2 = 0 [Yes] (C) 2 – 4 = 2 – 4 [Yes] (D) 2 - www.cracksat.net [Yes] (E) 4 – 2 = 2(2) [No] The correct answer is E. Don’t forget the EXCEPT! 13. A Do NOT try to figure out the seven numbers in the original list! The median is the middle number in a list of numbers. Because 8 is lower than every other number, and 43 is higher, they won’t change the value of the median. This means that option II is wrong, so you can eliminate B, D, and E. Because A and C both include I, you know it must be true without even checking it. Let’s focus on option III. The mode is the number repeated most often. Because 8 and 43 weren’t in the original list, they can’t change the mode. Eliminate C and pick A. 14. D There are variables in the answer choices, and the question asks you what must be true. This indicates that you will need to plug in values for x, possibly more than once. Try both –2 and 3. Only D remains true for both. Remember that the square of any nonzero number, either positive or negative, is always positive. 15. E Here’s the relationship: The smaller the shoes, the greater the difficulty. This is an inverse relationship. So, look for an inverse function. Only E is an inverse function. If you weren’t sure, try plugging in 8 and 10 for the s. The function should yield a greater D for 8 than it does for 10. Only E has D(8) > D(10). www.satpanda.com 16. D Note first that this is an EXCEPT question. Now, since a2b = 122, and b is an odd integer, let’s see what you can come up with. Let’s make b equal 1, so you get the following: a2 × 1 = 122 = 144, so a = 12. If a equals 12, it is divisible by 1, 2, 3, 4, 6, and 12. The only choice that remains is D. 17. D Since each side is a mysterious “x long,” let’s make up a value for x to make our lives a little easier. Let’s use 10, just because it’s nice and round. To find the area of the first triangle, you’ll have to find the height, which is the middle side of a 30°-60°-90° triangle. If the entire base is 10, then the height is 5 then A = bh = 10(5 ) = 25 . The area is . The second triangle has side lengths of 2x, which means each side is 20 long. We can find the area in the same way as the first one. We’ll end up with a height of 10 , and the area is 20(10 ) = 100 . Since the area of the second triangle is four times the area of the first one, the answer is D, 1 : 4. 18. A Keep in mind that this figure is not drawn to scale. Because , you know that the following angles are equal: ∠DCE, ∠CEA, ∠BCA, ∠CAE. Because triangle ACE has two equal angles, it is isosceles and the sides opposite those angles are also equal. Therefore, CE = AC = 3. www.cracksat.net 19. C Plug in numbers. If a = 10 and b = 10, then the inequality doesn’t work: (10 – 5)(10 + 5) = (5)(15) = 75, which is larger than 0, so eliminate answers D and E. If a = –5 and b = –10 then the inequality also doesn’t work: (–5 – 5)(–10 + 5) = (–10)(–5), which is larger than 0, so eliminate answers A and B, and C is the only answer left. 20. D Because 61 is the value of the second term in the sequence, plug in 2 for n: a3(2) – 3 = 61. Therefore, a6 = 64, and a must be equal to ±2. 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