<p>Can someone please explain how they got the 1/n(n+1) problem?</p>
<p>
</p>
<p>It’s a summation. i=1, n=50 for 1/(i(i+1)). I’ll admit I totally forgot how to do it so I just plugged it into my calculator and got 50/51.</p>
<p>sorry, im kind of lost. can somebody make a compiled list?D;</p>
<p>oh anddd whaats the 256 problem?</p>
<p>Wow, I just realized my mistake of the series one. </p>
<p>On the test, I put my calculator in sequence mode…
set the min to 1
Put u(n) = 1/(n*(n+1)) + u(n-1)</p>
<p>and set u(min) to… 1/3</p>
<p>It was 1/2 first… psh.</p>
<p>Anywho, I guessed it correctly. I’m still irked that I knew how to get the answer with the calculator but didn’t though. -_-</p>
<p>Also, how the heck do you do that problem without a calculator?</p>
<p>I could have used my calculator in retrospect, but I still got it. I just tried adding the first term, the first two, the first three, till I saw the pattern, which would be n/(n+1).</p>
<p>Fairly easy otherwise. Though I wasted ten minutes on the caffeine problem because I was being stupid. Avoided a dumb mistake though, I think.</p>
<p>I actually looked for a pattern.
(1/1<em>2) + (1/2</em>3) = 2/3
I added a couple more and found that the sum of the series is n/(n+1), so since they’re looking for the 50th term, the answer is 50/51</p>
<p>The 256 one was if c^d = 64 where c and d are both integers, what is one possible value of d^c?
Other possible answers include 81 and 36.</p>
<p>If there’s still debate over the hexagon problem i drew it out in paint to clarify things.</p>
<p>here u guys go</p>
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<p>Was the section with the knitting problem an experimental section? Also how do you do that one if anyone remembers, it had an inequality and something about rows and numbers 7 and 9. I omitted it since I didn’t understand the wording.</p>
<p>61 is definitely right for hexagon</p>
<p>it was
Figure 1 : 1
Figure 2: 1 + 6 <= 6 is first multiple of 6
FIgure 3: 7 (figure 2) + 12 <=2nd multiple of 6</p>
<p>As you can see there was a pattern in how much you add (a next multiple of 6)
thus with 19 you add 18 and with 37 you add 24 which equals 61</p>
<p>Knitting problem section was experimental.</p>
<p>Math was piece o’ cake! As long as I didn’t screw up simple mistakes.
One thing that stumped me was the radio one. I got 2/5 considering JUST the second radio, whilst 3/5 considering the chances for BOTH radios. I put down 2/5 because the problem states that the first one was a good one, but the phrasing was absolutely horrible… Oh and the summation one is 50/51 (the key is the second formula they give you, and to think of ALL the numbers between 1 through 51 as n starting at 1): (1/n)-(1/n+1) [this one is 1/(1)(2)]+ (1/n+1)-(1/n+2) [this one is 1/(2)(3), also note how the 1/n+1 cancels out because it was added then soon subtracted]… Eventually you’ll be left with (1/n)-(1/n+50) since the other ones just subtract/add each other out. Working all the way: 1/(1) - 1/(1)+50 = 50/51
Back to the radio, so was it 2/5 or 3/5?</p>
<p>It was 3/5 because it asked for the probability of picking a non-defective radio AFTER one non-defective radio was removed from the pool.</p>
<p>My bad, I switched the probability in my thing… But, yeah, I chose 3/5! So its a win-win!</p>
<p>So for the 50/51 problem, all you had to do was make n=1 and plug that into the second equation they gave you?</p>
<p>And did anyone have the problem where there were three variables and they told you the values of those variables in no particular order. Then you’re give that two of the variables are even and h>k (or something along those lines). Could someone please explain that one to me?
Thanks! :)</p>
<p>@theroyal
From what I remember the values were 4, 6, and 9 correct?
h>k
k is a square
j is an even</p>
<p>if k is a square, then the value will have to be 4 and 9
9 is the highest number in the problem, and since h > k, k=/= 9
k is 4, the remaining even is j (6 or something else), and the highest value is h</p>
<p>Okay. yeah… I did figure out k =/= 9 but that was pretty much all I could get. eeek ): oh well. But thanks!! ^^</p>
<p>hey guys. i figured out the sum of sequence one last minute. i knew that it was 50/51 but do you guys remember what letter that was? was that B or C??? ahh it’s annoying me cuz i didn’t have time to make sure i put down the letter for 50/51…i think i first put 49/50 down so i don’t know if i changed it to the right letter. i have no idea now. help??</p>
<p>B was 50/51, D was 49/50</p>
<p>WAIT
the radio question wasn’t 2/5?
…
why not… </p>
<p>does anyone remember the question…LOL</p>
<p>and whats the question with the boxes?</p>
<p>The radio question had 4 non-defective radios out of 6 total.</p>
<p>It asked you to find the probability of picking a non-defective radio after one of them had been removed. So, 4/6 –> (4-1)/(6-1) = 3/5</p>