Circle Graph

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

When a math question involves a table or chart, read both the text of the question and the labels of the chart carefully.  Identify the bottom line, and assess your options for solving the problem.  Attack the problem to find the answer, and loop back to make sure that your answer addresses the bottom line. In a survey, a group of students from Westville High School were asked about their favorite movie genre. Each student in the group selected exactly one movie genre, and the data collected are summarized in the circle graph above. If 40 more students chose Action than Fiction, how many students were surveyed in total?

Bottom Line:  Total students = ?

Assess your Options:  You could plug in answer choices for the total and then take percentages of those to find out which answer would produce a difference of 40 between Action and Fiction.  That would take a lot of steps!  Instead, start with what you know and use what you know to write an equation.

Attack the Problem:  You know that 40 more students chose Action than Fiction.  That means that Action – Fiction = 40.  You also know the percentages for both Action and Fiction.  Plug in the percentage from the chart and you will see that 30% (Action) – 14% (Fiction) = 16%.  Now you need to combine the two things that you know, percents and actual numbers, into a single equation.  You can write percents as decimals by moving the decimal two times to the left.  What are these percents of?  The uknown total number of students.  For any unknown number, you can plug in the variable x.  Now you have the equation .16x = 40.  Solve for x by dividing each side by .16 and you will get the answer 250.

Loop Back:  What did x represent?  The total number of students.  That matches your bottom line, so you are ready to look down at your answer choices.

(A) 100
(B) 150
(C) 200
(D) 250
(E) 300

The correct answer is (D).

On sat.collegeboard.org, 50% of the responses were correct.

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