Tham khảo tài liệu 'the gre quatitative section 5', ngoại ngữ, anh ngữ phổ thông phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | THE GRE QUANTITATIVE SECTION Multiple Probabilities To find the probability that two or more events will occur add the probabilities of each. For example in the problem above if we wanted to find the probability of drawing either a red or blue marble we would add the probabilities together. The probability of drawing a red marble 4. And the probability of drawing a blue marble -5-. 8 4 Add the two together J4 -jj ỳ. So the probability for selecting either a blue or a red would be 8 in 14 or 4 in 7. Helpful Hints about Probability If an event is certain to occur the probability is 1. If an event is certain not to occur the probability is 0. If you know the probability an event will occur you can find the probability of the event not occurring by subtracting the probability that the event will occur from 1. Special Symbols Problems The last topic to be covered is the concept of special symbol problems. The GRE will sometimes invent a new arithmetic operation symbol. Don t let this confuse you. These problems are generally very easy. Just pay attention to the placement of the variables and operations being performed. Example Given a A b a X b 3 2 find the value of 1 A 2. Solution Fill in the formula with 1 being equal to a and 2 being equal to b. 1 X 2 3 2 2 3 2 5 2 25. So 1 A 2 25. Example b If _ a b I a c I b c c b a a c Then what is the value of . . . 2 1 3 Solution Fill in variables according to the placement of number in the triangular figure a 1 b 2 and c 3. 4 -1 -1 -2y 210 --------------------------- THE GRE QUANTITATIVE SECTION ------------------------------------- Tips and Strategies for the Official Test You are almost ready to begin practicing. But before you begin the practice problems read through this section to learn some tips and strategies for working with each problem type. Quantitative Comparison Questions It is not necessary to find the exact value of the two variables and often it is important not to waste time doing so. It is important to use
