SAT math question

Test Preparation SAT Preparation
1

<li><p>If x = 5 y and y=z+1, what is x/5 in terms of z ?
(A) z
(B) z + 1
(C) 5^z
(D) 5^z +1
(E) 5^z +1</p></li>
<li><p>The sum of the positive odd integers less than 100 is
subtracted from the sum of the positive even integers
less than or equal to 100. What is the resulting
difference?</p></li>
</ol>

<p>Is 100 correct? I lost my answer key… </p>

<p>A large solid cube is assembled by gluing together
identical unpainted small cubic blocks. All six faces
of the large cube are then painted red. If exactly 27 of
the small cubic blocks that make up the large cube have
no red paint on them, how many small cubic blocks
make up the large cube?</p>

<p>125?</p>

2

<p>The 3rd problem is 125. </p>

<h1>15 The answer is 50</h1>

<h1>8</h1>

<p>The answer is B
x=5y y=z+1
x/5 = y</p>

<p>x/5 = z+1</p>

3

<p>oops, it was x=5^y . So its c then?</p>

4

<p>Yes the first one would be C then.</p>

5

<p>yes its C
x=5^y
y=Z+1 so X=5^(z+1) which yields x=(5)(5^z), ta---dah..
and for the cube one, picture something like , the inside, is a 3 by 3 by 3, which is no red paint, and it order to cover this 3 by 3,u need to make it 5 by 5 by 5so u cover top to bottom,and front to back. if 4 by 4 by 4(i think this is from oc,i was mad when i did this LOL), only covers half part of the solid.</p>

6

<p>Number 15 is 50, not 100</p>

<p>Oh and can someone explain the last problem?</p>

7

<p>op might get mad for us posting just the answers,so #15...
first set 2+4+6....+100
2nd set -(1+3+5....+99)
50 numbers, first set is 1 more than 2nd set for each number,so~~</p>

8

<p>explain to me how 15 is 50...</p>

9

<p>@zorro, the fact that 27 cubes are not painted let's you know that that's a 3 by 3 cube. You need to envision adding an extra "layer" of cubes onto the 3 by 3 cube. Only a 5 by 5 completely covers the 3 by 3. 5x5x5 = 125.</p>

10

<p>Thanks for the explanations everyone. I didn't really need them this time but its always good to have explanations.</p>

<p>And Ren, don't take my comments seriously. I'm never serious. Seriously.</p>

11

<p>i dont understand for the cube why it has to be 5<em>5</em>5, why not 4<em>4</em>4? I really dont understand what to do after you find the volume of the small cube which is 27.</p>

12

<p>because if it was 4<em>4</em>4 three sides of the 3<em>3</em>3 cube would be exposed, making them painted. </p>

<p>and i get 15 now. took me a second.</p>