Education.com

# Tip #49 to Get a Top SAT Math Score (page 3)

By Brian Leaf
McGraw-Hill Professional

1. Misbehaving Numbers (Skill 43), and Make It Real (Skill 16). A. Negative numbers with larger digits are smaller. Let's say m = –3. Then choice B equals 3m = 3(–3) = –9. And –3 is actually larger than –9.
2. Misbehaving Numbers (Skill 43), and Make It Real (Skill 16). C. Let's say p = –3. 1 – p is largest since 1 – p = 1 – (–3) = 4, while all other answers are negative.
3. Avoid Careless Errors (Skill 41) and Functions (Skill 14). A. Plug n in for x: m(n) = 2(3n)2 = 2 (9n2) = 18n2. Remember to square the 3 as well as the n, and then multiply by 2.
4. Logic (Skill 36). C. There are 42 yogis and 25 dungeon crawlers, so it would seem there are 67 total; but 18 are in both clubs, and have been counted twice. So at the joint meeting there are really 42 + 25 – 18 = 49.
5. Translation (Skill 26), and Finish the Question (Skill 42). E. Translate the words into math and solve:
6. 0.5x – 4 = 0.3x       add 4 to both sides

0.5x = 0.3x + 4       subtract 0.3x

0.2x = 4                  divide by 0.2

x = 20                     remember to finish the question

3x = 60

7. Median and Mode (Skill 34), and Use the Answers (Skill 1). E. When you see a median or mode question, rewrite the data as a list in order. Then try each answer choice. Choice E cannot be the value for p because it will make 7 tied with 3 as the mode.
8. B   Logic (Skill 36) or Make It Real (Skill 16). B. There seem to be m + p total members of sets M and P combined. Usually, we then subtract the common members (r) to determine the total, but in the "hard" question we subtract 2r since set Z contains no members that are in both. We are not just avoiding double-counting, but eliminating the common members entirely. So, set Z has m + p – 2r members.
9. Arrangements (Skills 31 & 32). 10. Since we have one-on-one competition, we have two spots to fill, so draw two blanks. Five competitors can fill the first slot, and four can fill the second slot. Then multiply 5 × 4 = 20. Because Juan playing Ezra is the same as Ezra playing Juan, we divide by 2 and get 20/2 = 10.
10. Probability (Skill 33), Donut Area (Skill 18), or Use the Diagram (Skill 21). C. Probability = , so the probability of hitting the shaded region is You could also just "Use the Diagram" and realize that no other answers make sense and that the shaded region being half the area of the larger circle is the only feasible answer.
11. Absolute Value (Skill 38) and Misbehaving Numbers (Skill 43). E. When you see an absolute value question, remember to consider not only the obvious answer, but also the less obvious one. x can equal 7 or –1, and y can equal 1 or –5. So the greatest possible value for xy = 7 – (–5) = 12.

Go to: Tip #50

150 Characters allowed

### Related Questions

#### Q:

See More Questions