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SAT MATH

SAT MATH. It is a trick. 1. A polygon has 90 diagonals. How many sides does it have?. d = n(n-3)/2. 90 = n(n-3)/2. 180 = n 2 – 3n. n2 – 3n – 180 = 0. (n – 15)(n + 12) = 0. n-15 = 0 or n + 12 = 0. n = 15 or n = -12.

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SAT MATH

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  1. SAT MATH It is a trick

  2. 1. A polygon has 90 diagonals. How many sides does it have? d = n(n-3)/2 90 = n(n-3)/2 180 = n2 – 3n n2 – 3n – 180 = 0 (n – 15)(n + 12) = 0 n-15 = 0 or n + 12 = 0 n = 15 or n = -12

  3. 2. If 3x + 5y = 14 and x – y = 6, then what is the average of x and y? 3x + 5y = 14 x – y = 6 4x + 4y = 20 x + y = 5 5/2

  4. 3. If a - b =1, b – c = 2, and c – a = d then find d a - b =1 b – c = 2 c – a = d 0 = 3 + d -3 = d

  5. 4. If p painters can paint h houses in d days, how many houses can five painters , working at the same rate, paint in two days? (A) dhp (B) 5hp (C) 2hp (D) 10h (E) 10dp 10 2d 5p dp h Pick 3 easy numbers Suppose that 1 painter can paint 1 house in 1 day. Try p =1, h = 1 and d=1 for the answer 10 E

  6. 5. It is now June, what month will it be in 100 months? 100/12 = 8 years with how many months left over? 4 months left over. October

  7. 6. In the below triangle find the value of a? 3a + 2a + 40 = 180 3a 5a = 140 a = 28 40 2a

  8. 7. The Riverdale Little League is divided into d divisions. Each division has t teams, and each team has p players. How many players are there in the entire league? d = 2, t = 5 and p = 15 2 * 5 *15 dtp

  9. 8. What is the value of n if 2 n+1 = 32 (B) 5 (E) 8 (A) 4 (C) 6 (D) 7 2 n+1 = 25 n + 1 = 5 n = 4

  10. 9. What is the value of a + b + c? 220 60 100 20 a b c 100 20 60

  11. 10. If the average of three consecutive integers is A, which of the following bust be true? I. One of the numbers is equal to A II. The average of the three integers is A III. A is an integer (A) I only (B) II only (C) III only (E) I, II and III (D) I and II only E

  12. 11. If m2 = 17 what is the value of (m+1)(m-1)? (m+1)(m-1)= m2-1 17 - 1 16

  13. 12. What is the value of n if 310 *272 = 92 * 3n (E) 30 A) 6 (B) 10 (C) 12 (D) 15 310 * ((3)3)2 = ((3)2)2 * 3n 310 * (3)6 = (3)4 * 3n 316 = 3n + 4 16 = n + 4 C n = 12

  14. 13. If a is increased by 10% and b is decreased by 10%, the resulting numbers will be equal. What is the ratio of a to b? (E) 9/11 A) 9/11 (B) 9/10 (C) 1/1 (D) 10/9 a + 10%(a) = a + .1a = 1.1a b – 10%(b) = .9b b - .1b = 1.1a = .9b a/b = .9/1.1 a/b = 9/11

  15. 14. In the figure at the right, C is the center of the circle. What is the value of c A Radii are =, so 55 c B C <BAC = 55 C = 70

  16. 15. If r, s, and t are different prime numbers less than 15, what is the greatest possible value for r + s t List primes < 15. 2, 3, 5, 7, 11, 13 What should t be, big or little? Small, so 2 Big, so 11 + 13 R and s should be ? 24/2 = 12

  17. 1. A polygon has 90 diagonals. How many sides does it have? a a a a a a

  18. 1. A polygon has 90 diagonals. How many sides does it have? a a a a a a

  19. 1. A polygon has 90 diagonals. How many sides does it have? a a a a a a

  20. 1. A polygon has 90 diagonals. How many sides does it have? a a a a a a

  21. 1. A polygon has 90 diagonals. How many sides does it have? a a a a a a

  22. 1. A polygon has 90 diagonals. How many sides does it have? a a a a a a

  23. 1. A polygon has 90 diagonals. How many sides does it have? a a a a a a

  24. 1. A polygon has 90 diagonals. How many sides does it have? a a a a a a

  25. 1. A polygon has 90 diagonals. How many sides does it have? a a a a a a

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