help on a few sat questions? thanks!

Test Preparation SAT Preparation
1

<p>Hi! My teacher gave us this sat prep practice sheet for the psat wednesday. I did it but have a few questions!<br>
*these were free response
1. x = the sum of all odd integers from 1 to 49 inclusive
y= the sum of all even integers from 2 to 50 inclusive
z= the sum of all integers from 1 to 48 inclusive
Based on above, what is the value of x + y - z
I got 99 but I'm not sure if its right! </p>

<ol>
<li>The average of 5 chains is 13 inches. If a 7 inch chain is added, the average length of the 6 chains is s inches. What is the value of s?</li>
</ol>

2

<ol>
<li><p>x = 1+3+5+7+9…+49 = 625
y = 2+4+6+8+10…+50 = 650
z = 1+2+3+4+5…+48 = 1176
625+650-1176 = 99
Or…
x + y - z = Everything cancels out until 49 and 50 = 49+50 = 99</p></li>
<li><p>average of 5 chains is 13 inch = sum is 65.
New sum = 72
New average = 72/6 = 12 inches;</p></li>
</ol>

3

<p>thanks a bunch!</p>

4

<p>can somebody help with this “identifying sentence error” question? its off the 2005S PSAT</p>

<ol>
<li>In the eighteenth century a simple method of musical notation helped to make music more popular than in any century
a. simple
b.helped to make
c. music more popular
d. any century
e. no error
thanks!</li>
</ol>

5

<p>@risbu, first off, please try to post your own thread next time instead of hijacking other threads.</p>

<p>And concerning your question, I’m confused between “Helped to make” and “Any century”. I’d suppose “helped to make” should be changed to “helped make”, but then that might not actually be a correction, and simply an error in daily speech. “Any century” seems more erroneous to me, in which the correction would be “any other century”. So yes, I’d go with D. Is that the correct answer?</p>

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<ol>
<li>D</li>
</ol>

<p>It should be any other century.</p>

<p>Any century would include eighteenth century as well as others, which is not what the sentence wants to say.</p>

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<p>Yes it’s d. sorry for not making my own thread just thought it would get quickly answered here since i posted quickly</p>

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<p>In regards to the first question, can anyone tell me how to add all those numbers so fast. I learned it before but I completely forgot the method. Thanks in advance!</p>

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<p>^ Patterns.</p>

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<p>For ttt </p>

<p>the “trick” that you’re most likley referring to is this:
x = the sum of all odd integers from 1 to 49 inclusive</p>

<p>x = 1 + 3 + 5 + … + 49 [there are 25 terms in the series]
x = 49 + 47 + 46 + … + 1 [re-write the series in reverse order]</p>

<p>Add the two series — note that the matching numbers each add up to 50 — 1+ 49, 2 + 48, etc. So you have 25 pairs each equal to 50.</p>

<p>2x = 25*50 or x =625</p>