Hard Math Problems- Need some help

Test Preparation SAT Preparation
21

<p>670, #4: It's OK, we all miss problems that seem embarrassingly easy sometimes.</p>

<p>You're probably thinking there must be some intuitive mathematical reasoning needed to solve this. There isn't. </p>

<p>Just count the number of squares in figure 1, and in figure 2, which comes out to 13 and 8, respectiely. They tell you the area of Figure A is 26 cm - so each square is 2 cm in area. So the area of figure 2 is 8 squares *2 cm = 16 cm.</p>

<p>Not every question on the SAT calls for deep mathematical knowledge :-)</p>

<p>683, #14: Now this is a problem which does require some mathematical knowledge. You have to know that in the equation of a parabola ax^2 + bx + c that if c is positive the equation is above the x-axis (and likewise, if c is negative, it is below the x-axis). Therefore E is the correct graph.</p>

22

<p>oops... too late</p>

23

<h1>20</h1>

<p>2)When 15 is divided by the positive integer k, the remander is 3. For how many different vaules of k is this ture?
a)1
b)2
c)3
d)4
e)5</p>

<p>If the remainder is 3, k must be a factor of 12 but not a factor of 15.</p>

<p>Factors of 12 = 1,2,3,4,6,12
Factors of 15 = 1,2,3,5,15</p>

<p>Values of k: 4,6,12</p>

<p>Answer: C</p>

<p>I dont really understand this... How is 2 a factor of 15?</p>

24

<p>
[quote]
How is 2 a factor of 15?

[/quote]
</p>

<p>It isn't, but you don't need the factors of 15 to answer this question.</p>

25

<p>BUMP, can someone re-explain #20, Why is 2 not counted, as that would clearly make 4 factors, not 3...</p>

26

<h1>20</h1>

<p>2)When 15 is divided by the positive integer k, the remander is 3. For how many different vaules of k is this ture?
a)1
b)2
c)3
d)4
e)5</p>

<p>The only options are 4, 6, and 12. </p>

<p>2 is not an option because 2 goes into 15 seven times with a remainder of 1. I see where you came up with that, though, as you were thinking through the factors of 12.</p>