# SAT Question of the Day (ACT too!): Oct. 28, 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=20131028&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.)

The answer is D.  This is a type of probability question and you can find my explanation of this topic under “mutually exclusive events” on my free website course and on Video #8.

If a student gets an A, she can’t get any of the other grades.  Getting any of the other grades excludes a student from getting an A.  That is, each grade excludes getting any of the others which makes them mutually exclusive.  The individual probabilities of related mutually exclusive events must add up to 1.  For this question, you know that getting an A, B, or C adds up to 19/20 or 95%.  That leaves 1/20 or 5% for getting a D.  We are told 10 students get a D which we calculated to be 1/20 of the whole population.  Therefore, p/20 = 10 or  .05p = 10; so, p = 200.

Check out my program for more sample questions like this one and other types of probability and combination questions you will see on the test.  I’ve also identified and  listed related questions that are in the Official SAT Study Guide and Real ACT Prep Guide for you.  That will make it easy for you to find and  practice this type of question.

In fact, many students have said they like how I’ve divided the universe of SAT and ACT math into 25 discrete topics plus the additional 4 unique ACT topics.  That allows them to easily identify their math strengths and weaknesses.  Then my math materials tell them exactly where to find related questions in the Official SAT Study Guide and Real ACT Prep Guide.  On top of that, the questions are categorized by difficulty level!  All of this allows you to have a personalized, efficient way to study for the tests–no wasted time.

I apologize for getting off topic but this is one of the answers to a question I get all the time: Why do students in my courses get such good results?

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

The answer is A.  There is no mistake in the original sentence.  All the other answers have grammar or composition errors.  B is present tense and the rest of the sentence is past tense.  C has the content problem of introducing “reality” when that isn’t the topic of the passage.  D is just silly; the airwaves can’t “realize” anything because they can’t think!

Be very careful when you take the test.  There will be answers that don’t require fixing anything — just like this one.  However, you are expecting a mistake and may see ones when there aren’t any because of your expectations.  Don’t create mistakes when there aren’t any.

The SAT & ACT Wizard