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Health & Fitness

This Isn't Math Class: Shortcuts in SAT Problem-Solving

SAT Math tips that fall outside the standard school curriculum.

 

The next two SATs will be on October 6th and November 3rd.  The deadline to register for the October exam is September 7th and the deadline for the November exam is October 4th.

Working on SAT math problems brings back memories of math teachers of years past.  You remember who taught you about x and y for the first time.  Who brought you the magic of matrices? And who nearly brought you to tears with geometric proofs?  Ah their faces are clear.  But do you have to remember everything they taught you to cover the Algebra, Geometry and Algebra 2 sections of the SATs?  Luckily, the answer is “no.”

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Let’s take the following example:

If 2x+ 5y = 15, then what is the value of 12x + 30y?

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Math Teacher X may have taught you to try solve for a variable when given such an equation, but on this problem, it is not necessary.  Do you see that there is a relationship between the two equations in that their individual terms are in equal proportion?  The second equation’s first term is six times that of the first equation’s first term and so are the second terms similarly related.  Therefore the second term must equal six times the first.  Find the answer by again multiplying the 15 by 6. The answer is 90.

Here’s another example:

If 3a/2b = 1/3 and b/5c = 4, what is the value of a/10c?

The number of variables involved here make is seem like solving algebraically would be very difficult.  But the student who is on the lookout for relationships between given terms will notice that multiplying 3a/2b by b/5c will get you 3a/10c which is very close to the term in question.  If all one needs to do is divide by 3 to get to a/10c, then substitute the real numbers, multiply them together as well and at the end divide by 3.  1/3 x 4 = 4/3.  Divided by 3 = 4/9 which is the answer.

Looking for short-cuts by determining the relationships between the parts of a problem is not something you may have practiced in your math class, but the College Board test writers seem to be partial to these kinds of problems with hidden clues.  Whenever a problem with multiple variables seems impossible, be sure to go on the hunt for short-cuts.

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