SAT Question of the Day (ACT too!): Nov. 21, 2013

If you are reading this in an email you received from me, do not click the link to sat.collegeboard.org below. Use the link to my website that is farther down on the email.

If you are seeing this in my blog, do the SAT Question of the Day by clicking on this link:

http://sat.collegeboard.org/practice/sat-question-of-the-day?questionId=20131121&oq=1 (This link takes you to today’s question. If you use my archive, you will see the question related to my SAT explanation for that date.)

This question is really hard based on the number of students that is getting it correct: 37%.  However, the math is simple; it’s the reasoning that’s making it difficult.  You just don’t get asked to do this in your regular math class.  It would be a good question to have your math teacher do today.  Then show your class my explanation.

I love these kinds of questions.  They truly are puzzles that provide a little challenge that is outside the typical box!  There’s a similar one in my Demystifying the SAT & ACT manual on page 71, #7.  It is also on my website  (Math Logic or Patterns, Question #12).  Take a look at it for more practice.  Students often ask why I put this type of question in my materials.  That’s an easy question to answer–my guarantee is “no surprises on test day.”

The answer is A.  The test writer’s explanation on the College Board website is the typical way to do the question and it is worth reading.  I started doing it their way but part way through the process I realized there’s a shortcut that saved me some time.  Once I did “if the tens digit is 1 and doubled it to get 2, I knew there are 7 units digits that are larger.  At that point, I though to myself, “I bet there’s a pattern.”   Do you remember my mantra: The world of math is a world of patterns?”  Then I tried 2 as the tens digit and got 5 units digits.  At that point, I knew the pattern would be 7, 5, 3, 1 without doing any more examples.  That gave me 16, Answer A.

Wasn’t that fun?  Practice these kinds of questions and remember to think, think, think.  They will always look easy but there is almost always some silly little thing most students forget.  Be careful.

Let’s see what the ACT folks have for us this morning.