Blue Book Q 12, 13, 14 pg 475

<p>Sorry, I found these hard x.x</p>

<p>12) If x^2 - y^2 = 77 and x + y = 11, what is the value of x?</p>

<p>13) Tameka cut a circular pizza into wedge-shaped pieces, one of which is shown above. The tip of each piece is at the center of the pizza and the angle at the tip is always greater than 20 degrees, but less than 30. What is one possible value for the number of pieces into which the pizza is cut?</p>

<p>14) a, 3a ...
The first term in the sequence above is a, and each term after the first is 3 times the proceeding term. If the sum of the first 5 terms is 605, what is the value of a?</p>

<p>I'd appreciate explanations!</p>

<p>P.S. Does anyone recommend a good program for the math portion and SAT II Math IIc test besides SAT OS (since it doesn't cover everything)</p>

<p>Thanks!</p>

<p>12) Just substitute it in.
x+y = 11, y = 11 -x ---------- (1)
x^2 - y^2 = 77 -------------- (2)
x^2 - (11-x)^2 = 77
x^2 - 121 - x^2 + 22 x = 77
-121 + 22x = 77
22x = 198
x = 9
y = 2</p>

<p>13) The pizza altogether the angle is 360 degrees. So you want to know, 360 can be split into how many pieces, with each piece between 20 degrees to 30 degrees?</p>

<ul>
<li>Max number of pieces: 360 / 20 = 18</li>
<li>Min number of pieces: 360 / 30 = 12</li>
</ul>

<p>Just put in any number in between (not including) 12 and 18, so maybe 15? You know it works, cuz 360 / 15 = 24 degrees</p>

<p>14) a + 3a + 9a + 27 a + 81 a = 121 a = 605
a = 5</p>

<p>Wow,
You make it seem so easy!
Thank you so much!</p>

<p>fiona, you could have left one for me...</p>

<p>12) If x^2 - y^2 = 77 and x + y = 11, what is the value of x?</p>

<p>x^2 - y^2 = (x+y)(x-y) = 11(x-y) = 77
thus, x-y = 7
and x + y = 11
therefore x = 9.</p>

<hr>

<p>13) Tameka cut a circular pizza into wedge-shaped pieces, one of which is shown above. The tip of each piece is at the center of the pizza and the angle at the tip is always greater than 20 degrees, but less than 30. What is one possible value for the number of pieces into which the pizza is cut?</p>

<p>360/30 < n < 360/20
---> means 12<n<18</p>

<hr>

<p>14) a, 3a ...
The first term in the sequence above is a, and each term after the first is 3 times the proceeding term. If the sum of the first 5 terms is 605, what is the value of a?</p>

<p>Sum of 5 terms of the Geometric progression = a(3^5 - 1) / (3-1)
605 = a (242)/2
a = 605/121 = 5</p>

<p>;)</p>

<p>A circular logo is enlarged to fit the lid of a jar. The new circumference is 50 per cent larger than the original. By what percentage has the area of the logo increased?
(A) 50%
(B) 100%
(C) 125%
(D) 225%
(E) 250%</p>

<p>Here's one lol, cheers to you Nov-SAT-takers</p>

<p>New circumference = 1.5 (2.pi.r)
means new radius is 1.5 times original radius.
Area = pi.R^2 = pi.(1.5r)^2 = 2.25 pi .r^2
So the area has increased by 125%</p>

<p>That was for shiomi! P:</p>

<p><em>turns this into a lounge discussion</em></p>

<p>Everyone on CC answers 3 questions a day. But fiona<em>, feeling acquisitive, decided to take on 10 questions a day. This graph is described as </em>________</p>

<p>A. skewed to the left
B. skewed to the right
C. symmetrical
D. Not enough infomation</p>

<p>^E. anhtimmy has too much time on his hands :D</p>

<p>Faster way (imo) to think about the first problem...they have to be integers, i think I did that problem and that's what it says. So just think, what is a perfect square that is close to 77 that subtracts something to get there? Well...9^2 is 81, and 81-4=77. Yay, less math.</p>