GRE Math Study Guide Exam.

GRE Math Study Guide Exam. formula for distance problems - CORRECT ANSWER distance=rate×time or d=rt The Perimeter of a rectangle - CORRECT ANSWER P=2(l+w) The Perimeter of a Square - CORRECT ANSWER P=4s (s=side) Area of a Parallelogram: - CORRECT ANSWER A=(base)(height) (x-y)(x+y) - CORRECT ANSWER x²-y² (x-y)² - CORRECT ANSWER x²-2xy+y² (x+y)² - CORRECT ANSWER x²+2xy+y² An Angle that's 180° - CORRECT ANSWER Straight Angle The sum of all angles around a point - CORRECT ANSWER 360° If a pair of parallel lines is cut by a transversal that's not perpendicular, the sum of any acute angle and any obtuse angle is - CORRECT ANSWER 180 Acute Angle an angle that is less than 90° Obtuse Angle:angle that is greater than 90° but less than 180° Distance - CORRECT ANSWER (rate)(time) d=rt Rate - CORRECT ANSWER d/t (distance)/(time) Time - CORRECT ANSWER (distance)/(rate) d/r How do you solve proportions? a/b=c/d - CORRECT ANSWER Cross multiplication a/b=c/d 4/6=10/15 4(15)=6(10) 60=60 If a lamp increases from $80 to $100, what is the percent increase? - CORRECT ANSWER = 25%. = (actual increase/original amount) x 100% = 20/80 x 100% = 1/4 x 100% = 25% The percent decrease of a quantity - CORRECT ANSWER = (actual decrease/Original amount) x 100% If a lamp decreases to $80, from $100, what is the decrease in price? - CORRECT ANSWER = (actual decrease/Original amount) x100% = 20/100x100% = 20% To increase a number by x% - CORRECT ANSWER multiply by 1+x% i.e. 100 x (1+50%)=100x1.5=150 To decrease a number by x% - CORRECT ANSWER multiply by 1-x% i.e. 100 x (1-50%)=100x.5=50 THE DENOMINATOR CAN NEVER - CORRECT ANSWER BE ZERO! 1/∅=null If ab then - CORRECT ANSWER -a-b The reciprocal of any non-zero number is - CORRECT ANSWER 1/x Probability of an Event - CORRECT ANSWER P(E) = number of favorable outcomes/total number of possible outcomes If Event is impossible - CORRECT ANSWER P(E) = ø If E is certain - CORRECT ANSWER P(E) = 1/1 = 1 Probability of Event all cases - CORRECT ANSWER ∅≤P(E)≤1 Probability of E not occurring: - CORRECT ANSWER 1 - P(E) Circumference of a circle - CORRECT ANSWER pi(diameter) Circumference of a circle - CORRECT ANSWER 2(pi)r Area of a circle - CORRECT ANSWER (pi)r² Volume of a rectangular solid - CORRECT ANSWER (length)(width)(height) Volume of a cube - CORRECT ANSWER edge³ Vertical lines - CORRECT ANSWER Do not have slopes! Any Horizontal line slope - CORRECT ANSWER zero Slope of any line that goes up from left to right - CORRECT ANSWER Positive