Discussion in 'Odds & Ends' started by tennis_nerd22, Aug 28, 2008.
Well, an integer multiplied by an integer will always give you an integer.
So if we take the first part to be 5 for all options , only option 1 gives the exponent part as an integer (10^5)
The other 2 have the exponent part as decimals.
First of all, you should help out we readers by using the carrot "^" to indicate exponents. Then the first choice I. would read, 1.25 x 10^17. See? So we could make the first factor bigger by moving the decimal over two places, to compensate, we must move the decimal for the second factor over two places in the opposite direction. Then we get 125 x 10^15. This looks different, but has the same value as before. 125 = 5^3, and 10^15 = (10^5)^3, so each factor is an integer cubed, so the product is also a cube.
But for III. they make a mistake. This time we move the decimal over three places. So we re-write it as: 125 x 10^-15. 125 = 5^3 and 10^-15 = (10^-5)^3. But they're forgetting that 10^-5 is NOT an integer. We expressed it using integers, but it is 0.00001, clealy not an integer. Therefore the correct answer is A, not D.
(I don't like to quickly say that an answer guide is wrong. So I double-checked these on a calculator. Put them in a calculator one at a time, then take the cube root. If the cube root is an integer, then x could be an integer as well.)
wow, i took an extremely rigorous and comprehensive sat class this summer and have never seen a problem as hard as that....
thanks for the explanation.
and about the exponents, i copy+pasted and wrote the thread really quickly and i had no idea that the ^'s were missing.. i guess i should have realized cuz on the actual website they were in superscript. sorry about that
really? lol that question was worded in a weird way but.. yea i hope i dont see it on the actual test lol
did u take the reading/writing too? like the SAT reasoning test?
haha i guess so.. iunno i found it a pretty helpful site. everyone makes mistakes i guess? haha
realistically, it's not a hard question it's not even a math question honestly. It's a linguistics question. First off what is the definition of an integer? A whole number.
I 1.25 x 10^17
II 12.5 x 10^-12
III 0.125 x 10^-12
I) would yield a whole number
II) would yield NOT a whole number
III) would yield NOT a whole number
If you can use a calculator, simply type out:
1 note to remember is that wrong answers count against you on this test o-o. I never learned that until I started taking the LSAT haha.
GL on the test
pretty much all i did for 6 weeks was do sat problems. overall, the test is easy. the material is set at a level where most people can take it and do reasonably well. the math material is extremely easy. nothing past maybe algerbra and geometry. they get you with their tricks. see through them and you should do fine. english is a little tougher. writing is mostly grammar. if you knock the question section out of the park, you dont need a perfect essay grade to get an 800. for reading, one word; vocab! study your vocabulary words and your score WILL go up. of course reading comprehension is important but vocab is really big in the reading section.
hope that helped
Separate names with a comma.