MCAS Strategy of the Week

Process of Elimination

What is it? The process of elimination is a test-taking strategy to use when you are unsure of the answer to multiple choice questions. When you take a random guess at a multiple choice question, you have a 25% chance of answering the question correctly. (That is a pretty good chance, so don't leave any questions unanswered!) When you eliminate noticeably wrong answers, your chances of answering the question correctly increase to 33% or even 50%!

Practice this strategy at home!

The question below was taken directly from the 2017 Mathematics MCAS.
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How do I use process of elimination to answer this question?

Identify key words - "Perpendicular" is bolded - that must mean it is important!

Use prior knowledge to eliminate incorrect answers - In Algebra 1, students learned that the slope of parallel lines, two lines that never intersect, is the same (memorize this!) Given this information, and knowing that perpendicular lines do intersect, you can eliminate option B! Cross it out on the test.

Now it gets tricky. How about drawing two perpendicular lines? Compare the slopes. One will increase, the other will decrease, that tells us that since the original line is negative (decreasing slope), the line that is perpendicular should be positive. Cross out option A!

Perpendicular slopes have the opposite reciprocal. Memorize this! Look at the drawing again - this makes sense! Eliminate option C and you're left with the correct answer - D.