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http://sat.collegeboard.org/practice/sat-question-of-the-day?src=R&questionId=20130317 (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.)
Here’s wishing you a fine St. Patrick’s Day!
The answer is B. I plugged in numbers, substituting the concrete (actual numbers) for the abstract (a and b). For answer A, if a=0, then there’s no positive number (the absolute value of b) that I can subtract from 0 that results in 5. Every answer has to be negative. B works fine since if a=5, then 5-0 (for b=0), the answer is 5. C and D result in 0. For answer E, there’s no positive number that you can subtract from 1 that can give you more than 1.
Changing the abstract to the concrete is a very powerful strategy. A student told me she used the technique “a lot” on the March SAT. My count of questions on released tests where the strategy works is about 20%. It is often much more efficient than doing the math while using variables that you are given.
Let’s see what the ACT folks prepared for us today.
http://www.act.org/qotd/ (The ACT staff does not put a date on their questions so if you click on an archived blog, you’ll get today’s question and the old explanation. Sorry. The SAT staff has dated their questions; so, the archive is helpful. The ACT folks simply don’t do that.)
The answer is A. Be careful; the question asked “would NOT confirm.” Looking at the chart, you can see if you have a sample with a concentration of a specific amount of anything other than 02 (oxygen), it will match an entry in the chart for either a depth of 15 or 20. If it is zero for oxygen, you can’t tell what the depth is. It could be 10, 15, or 20.
This question is a good example of how to prepare for the ACT Science Test. Practice reading charts and graphs. Work on your speed. Don’t waste time reviewing science topics; you couldn’t possibly figure out what to review since the science knowledge that shows up on the test is very unpredictable.
Enjoy your day.