random math qs

Test Preparation SAT Preparation
1

<p>-When they use the word "between," do they mean inclusive or exclusive?</p>

<p>-Every year Jack's investment of $700 increases by 5%. In which year will his investment first exceed $1000? </p>

<p>I got 9, because 700*1.05^(9-1)=1034. But the prep book, McGraw Hill, says its 8. So the problem regards subtracting the 1 in the exponent and how you define the first year. So what's up with this? On the real test, what would CB go with?</p>

<p>By the way, have any of you used the McGraw-Hill SAT Math workbook? The practice problems are good, but the typos make me wince. They even give wrong answer choices. For one of the problems all the choices were multiples of sqrt2, but the right answer was a multiple of sqrt5. So anyone considering purchasing this book--beware! You will probably be better off with the more popular Barrons or PR books, if you're looking for practice questions harder than CB's own. </p>

<p>Thanks!</p>

2

<p>"Between" usually means "exclusive". E.g., the number of primes between 2 and 17 is five, not seven.</p>

<p>I wouldn't worry too much about "one-off" problems like that investment one (especially since your mah was fine). The CB/ETS works pretty hard to ensure that every problem is clear and can't be interpreted in ways that lead to different but possibly correct answers. Quite a few review books have poorly worded problems and even painful typos, which I guess you've discovered!</p>

3

<p>Oh wait, Isn't the formula is Total Value = Initial Value + (Pecent Increse + 1)^Number of years.............</p>

<p>So, 1000=700+(1.05)^N
If you plug in 8, the equation works.</p>

<p>I did this equation earlier this year, so I am almost certain I am right.</p>

4

<p>Muchos gracias.</p>