7.SO, THE PROBABILITY FOR SELECTING EITHER A BLUE OR A RED WOULD BE 8...
7
.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 notoccurringby 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 newarithmetic operation symbol. Don’t let this confuse you. These problems are generally very easy. Just pay atten-tion to the placement of the variables and operations being performed.Example:
Given ab(a b3)2
, find the value of 1 2.Solution:Fill in the formula with 1 being equal to aand 2 being equal to b.(1 2 3)2
(2 3)2
(5)2
25. So, 1 2 25.bIf = _____ + _____ + _____a − b a − c b − cc b aac2Then what is the value of . . .31Fill in variables according to the placement of number in the triangular figure:a1,b 2,and c3.2
+1 –
2
3
+2 –
1
3
=–
3
1
+ –1 + –1 = –2
1
3
1 –
3
T i p s a n d S t r a t e g i e s f o r t h e O f f i c i a l Te s t
You are almost ready to begin practicing. But before you begin the practice problems, read through this sec-tion 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 notto wastetime doing so. It is important to use estimating, rounding, and the eliminating unnecessary informa-tion to determine the relationship.■
Attempt to make the two columns look as similar as possible. For example, make sure all units are equal.This is similar to a strategy given in the problem solving section, and it is even more applicable here.This is also true if one of the answer choices is a fraction or a decimal. If this is the case, make the otheranswer into an improper fraction or a decimal, which ever is going to make the choices the most similar.■
Eliminate any information the two columns share. This will leave you with an easier comparison. For exam-ple, if you are given the two quantities: 5(x1) and 3 (x1), and told that xis positive, you would select thefirst quantity because you can eliminate the (x1) from both. That leaves you to decide which is greater, 5 or