<p>I have done a bunch of college board practice tests, and none of them have questions like</p>
<p>...how many ways can you arrange this..??
...if the car travels 4km/h and travels a distance 20 km, how long did it take?</p>
<p>and other combination/ permutation questions!</p>
<p>because in the prep books that i'm doing, (princeton review) they give a bunch of these sorts of questions! but even on my actual march SAT, there were no math questions of the types mentioned above! and i've done 5 other college board tests and they don't have them, so i'm unsure if we really need to know these concepts for the math section? </p>
<p>Thank you so much if you can answer!!!</p>
<p>These types of questions come up once in a while as level 5 problems. So if you want an 800 on the test you should know these concepts.</p>
<p>Also, there are many easier questions where you can use d=r*t, combinations or permutations, but you don’t need to.</p>
<p>could someone confirm this please 
thankss!</p>
<p>They show up every so often, but there’s almost always an alternative way to solve them. And they’re very simple if they do show up.</p>
<p>There are definitely problems that show up that require the counting principle (where you multiply the number of options you have for each decision or step in the process). There are at least a half-dozen of these to be found in the blue book.</p>
<p>There are occasionally problems where you COULD apply combinations and permutations but these problems are always solvable by “brute force” – listing and counting. So if you are not comfortable with nCr and nPr, you don’t have to use them on the SAT. </p>
<p>And yes, you should know that rate x time = distance!</p>
<p>I agree with everything pckeller said, BUT I would suggest that students that want to get an 800 should be comfortable with permutations and combinations - you don’t need to know the formulas since your calculator can do this, but you should know how to recognize them. </p>
<p>Most students can get away with just having a basic understanding of the counting principle.</p>
<p>It is true that the number of questions on counting/permutations and distance/rate typically don’t exceed one or two of each type in a test.</p>
<p>Here are some statistics from recent official SAT QAS tests.
MAY 2011: counting/permutations: 1: distance/rate: 0
JAN 2011: counting/permutations: 0; distance/rate: 0
OCT 2010: counting/permutations: 2; distance/rate: 0
MAY 2010: counting/permutations: 1; distance/rate: 0
JAN 2010: counting/permutations: 1; distance/rate: 0
OCT 2009: counting/permutations: 0; distance/rate: 1
MAY 2009: counting/permutations: 1; distance/rate: 0
JAN 2009: counting/permutations: 1; distance/rate: 0</p>
<p>I would recommend that you understand how to apply the basic counting principle, and also the conceptual difference between permutation and combination. Also, there are not that many distance rate problems that show up on the SAT, but when they do they tend to be on the difficult side.</p>
<p>Here is one that was the last grid-in question on one of the official tests( I can’t recall the year)
Diana ran a race of 700 meters in two laps of equal
distance. Her average speeds for the first and second
laps were 7 meters per second and 5 meters per second,
respectively. What was her average speed for the entire
race, in meters per second?</p>
<p>Cheers,
Dabral</p>