Saturday, August 25, 2012

Logic

Read the following SAT test question and then select the correct answer. 

The Knowsys math method calls for you to read each question carefully, but you should be especially conscious of the possibility of misreading when your question involves a graph.  Be sure that you understand each label on the graph and take the time to read any additional information given in the question.  Identify the bottom line and asses your options for solving the problem in an efficient manner.  Select your method, attack the problem, and loop back to make sure that the answer you found fits the bottom line, that it answers the question that you were asked.

 graphic

The bar graph above shows the number of people in attendance at each of the four meetings of the Maple Street Block Association that were held in 2011. Only members of the Block Association can attend the meetings, and no members joined or left the Block Association during 2011. Based on the bar graph, what is the least number of members the Maple Street Block Association could have had in 2011?

 Your bottom line is the least number of members belonging to the association.  You must use logic to determine which information in this graph is relevant.  The question is meant to mislead you, because as soon as you see the word “least,” you are likely to look for the smallest value on this bar graph.  Before you jump to any conclusions, think about what the bar graph represents.  At any of these four meetings, all of the members could have shown up, or only some of the members.  In other words, it is possible for people to be absent, but it is not possible for people to be at these meetings without being members.  All of the people present at any meeting must be members.  The greatest number of people who came to any meeting is 72.  Therefore, there cannot be fewer than 72 members in this club.  Look down at your answer choices.

(A) 61
(B) 65
(C) 67
(D) 72
(E) 268

The correct answer is (D).


On sat.collegeboard.org, 43% of the responses were correct.

For more help with SAT math questions, visit www.myknowsys.com!

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