Are you smarter than your sixth grader?

Question 1: Have the (+) and (-) signs been around since 1489 or 1689?
or

Question 2: How many workers did it take to build the Taj Mahol in India during the 1600's?

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Question 3: How many muscles are there in the human body?

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Question 4: What was the average U.S family income in 1915?

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Question 5: What is the name of an angle measure > than 90 degrees but less than 180 degrees?

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Parents

Information for this quiz was obtained at http://www.funtrivia.com/quizzes/sci__tech/math/mixed_math.html.