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<p>First, sorry for the double post. Unfortunately, I am unable to edit posts on my cell phone.</p>

<p>I have stumbled across an SAT problem that perplexes me profoundly. Here it goes:</p>

<p><if a,="" b,="" c="" and="" f="" are="" four="" nonzero="" numbers,="" then="" all="" of="" the="" following="" proportions="" equivalent="" except…=""></if></p>

<p>A) a/f = b/c
B) f/c = b/a
C) c/a = f/b
D) a/c = b/f
E) af/bc = 1/1</p>

<p>There is no restriction on these numbers except they are unequal to zero. Heck, they could be everything! I could arbitrarily assign numbers to the equations that every single one of them works. What are we looking for here?</p>

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<p>^^Is the answer E?</p>

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<ol>
<li>The median of a list of 99 consecutive integers is 60. What is the greatest integer in the list?</li>
</ol>

<p>A: 109. What’s the quickest & most easiest way to get this answer?</p>

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<p>@HelloParis, since there are 99 integers and 60 is in the middle, you can conclude that 60 is the 50th integer and that there are 49 integers before it and 49 integers after it (49 + 49 = 98, and with 60 in the middle, that makes 99 integers). So 60 + 49 = 109</p>

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<p>@MuffinMan17 Thank-you! That makes much more sense now!</p>

<p>Can anyone explain this question to me?</p>

<ol>
<li>Let the function f be defined by f(x) = 5x for all numbers x. Which of the following is equivalent to f(p +r)? </li>
</ol>

<p>A: 5p + 5r (Why is not 5p + r?)</p>

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<p>Remember that since you have f(x) equals something, you have to plug in p + r in for x. So, this will be f(x) = 5x and you substitute (p + r) in for x. It’ll be f(p+ r) = 5(p + r) which is 5p + 5r. Just pretend that you put parentheses around x before you substitute things in the function, so you’ll f(x) = 5(x)and then you can plug in p + r in for x.</p>

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<p>@MuffinMan17 I totally forgot to distribute! Thank-you so much again! :)</p>

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<p>No problem! I’m here anytime for math help! :)</p>

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<p>No, the solution is A.
This is an example from the blue book o.O</p>

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<p>^^ Ah! Then I don’t know, haha. I do have the solutions and explanations though. Can you tell me what number it is and what page it’s on?</p>

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<p><a href=“http://imageshack.us/a/img16/5866/94192449.png[/url]”>http://imageshack.us/a/img16/5866/94192449.png&lt;/a&gt;&lt;/p&gt;

<p>for 12 bottles of shampoo of various brands,the cost and volume of each are displayed in the scatterplot above and the line of best fit for the data is shown.of the following,which is closest to the average cost per ounce for 12 bottles?
a)0.06
b)0.09
c)0.12
d)0.15
e)0.18
…
I did it but did without empirical analysis…could you tell me how should i approach this kind of questions?</p>

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<p>The average cost per ounce is just the slope of the least squares line. Looking at the graph, the slope is around $5/40 oz ~ 12 cents/oz, C.</p>

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<p>Thanks for the quick response!</p>

<p>My question was actually how i know that the line demonstrates average…
what encouraged you to think so?</p>

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<p>That’s what i found “A line of best fit is a straight line that best represents the data on a scatter plot.<br>
This line may pass through some of the points, none of the points, or all of the points.”</p>

<p>So when i find “best fit line” i should know what?
That it demonstrates average…is their anything?</p>

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<p>@muffinman: it’s p705/19. Looking forward to your reply!</p>

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<p>@Europeen, I’ve got your answer. It’s really stupid, haha, but I’ll copy and paste what the sat answer explanation says.</p>

<p>Choice (A) is correct. In choice (A), by cross multiplying (a/f) = (b/c), it follows that ac=fb. From each of the proportions given in the other answer choices, it follows that af=bc. Therefore, the proportions in options (B) through (E) are equivalent to each other but not to the proportion in (A).</p>

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<p>How do you do this problem?

<a href=“http://i1258.■■■■■■■■■■■■■■■/albums/ii523/aroojmohammed/IMAG0070_zpsef823db9.jpg[/IMG]”>http://i1258.■■■■■■■■■■■■■■■/albums/ii523/aroojmohammed/IMAG0070_zpsef823db9.jpg

</a></p>

<p>Why isn’t the answer 90? I did A1 + A2 = (A3+ A4) /2 and 90 was the only value that worked. The answer was 60.</p>

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<ol>
<li>For which of the following values for k will the system of equations above have NO solution?</li>
</ol>

<p>3x + 7y = 12
6x - ky = 6</p>

<p>A: -14</p>

<p>I got 14. Can anyone explain why there’s a negative sign?</p>

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<p>3*2 = 6.</p>

<p>7*2 = 14</p>

<p>So k should be -14 to make the second equation 6x + 14y = 6.</p>

<p>In this case the left hand side of the second equation is twice the left hand side of the first equation, but the right hand side is not.</p>

<p>If k were 14, then the system would have a unique solution.</p>

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<p>@arooj1a2b3c: you have it right with that equation. Your equation says the area of the shaded regions is twice that of the unshaded. So, 60+60=120 and the angle for the shaded is 360-120= 240, which is twice that for the unshaded. </p>

<p>90 would be correct of the unshaded and shaded had equal area</p>