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05-09-2008, 07:38 PM
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#76 | | Member
Join Date: Jan 2008
Posts: 764
| Man I'm kicking myself for missing two easy parts, 2b and c (die stupid mistakes die...). Other than that and 6b (yay another certain type of mistake), I believe I did well. Hope the same for all of you. | 
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05-09-2008, 07:50 PM
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#77 | | Junior Member
Join Date: Apr 2008
Posts: 43
| darn. i thought the 2000 was a rate that continues when the time increases. so i put: 2000t-400sqrt t. no wonder i couldn't find a max.  | |
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05-09-2008, 08:14 PM
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#78 | | Member
Join Date: May 2007
Posts: 428
| Quote: Posted by Sheed30
I'm pretty sure you all got 2d wrong.....you have to add 120 tickets i think because there were 120 pre-sold tickets....so the answer would be 1093.....right?
| The 120 number comes from the number of people waiting in line at t = 0. That doesn't mean that 120 tickets were pre-sold. | |
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05-09-2008, 10:39 PM
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#79 | | Junior Member
Join Date: Jan 2007
Posts: 112
| Well, it wouldn't make sense if 120 people waited in line and didn't buy tickets, or am I wrong? I think what they were testing you was that whether or not you could identify the initial condition, so I think Sheed30 is right. | |
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05-09-2008, 10:45 PM
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#80 | | Member
Join Date: May 2007
Posts: 428
| Who said they didn't buy tickets? I'd argue that the 120 people who were in line at t=0 were probably the first 120 tickets sold, as prescribed by the r(t) function describing the rate of ticket sales. But just because a line exists before tickets officially start selling doesn't mean that they bought the tickets beforehand. In fact, it usually means quite the opposite.
Just ask all the people who were camped out in front of Best Buy the day that Grand Theft Auto 4 first sold whether they already have a copy or not. And if they already have a copy, why are they waiting in line? | |
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05-09-2008, 11:01 PM
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#81 | | Junior Member
Join Date: Jan 2007
Posts: 112
| TheMathProf, I feel pretty stupid here, I'm not getting your arguement as it seems contradicting to me, so would you add the 120 or not and why? | |
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05-09-2008, 11:07 PM
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#82 | | Member
Join Date: May 2007
Posts: 428
| I would not add 120. The presence of a line for people waiting to buy tickets at time 0 does not mean that those people bought the tickets before time 0. They probably did buy tickets, but after time 0, and are already accounted for in the r(t) equation that is already provided. When we take the integral from 0 to 3 of r(t) dt, my claim is that those people in line at time t = 0 are already being counted, and therefore, adding 120 to the integral will double-count them.
Sheed30's argument seemed to be that 120 tickets were already sold at time t = 0, and thus needed to be added to the accumulation, at least as I understand the argument. My counter to that is that the 120 people were merely in line, and thus had not yet purchased tickets, and that therefore there was no initial value of ticket sales that needed to be accounted for. | |
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05-09-2008, 11:21 PM
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#83 | | Junior Member
Join Date: Jan 2007
Posts: 112
| Oh, I see what you mean, darn it, I got it wrong then. How many points do you think I lost for adding 120 to the final answer? | |
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05-09-2008, 11:29 PM
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#84 | | Member
Join Date: Dec 2007 Location: PA
Posts: 902
| i just watched Stand and Deliver.. weird haha | |
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05-09-2008, 11:29 PM
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#85 | | Member
Join Date: May 2007
Posts: 428
| Probably 1 at the most, nanoscaled. | |
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05-10-2008, 12:30 AM
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#86 | | Junior Member
Join Date: Apr 2007
Posts: 134
| I don't understand 3c. I'm sure you guys are right, but I felt the question was not consistent with 3b. Since 60,000 cubic cm oil has already leaked, shouldn't the time be starting at 30 (constant rate of 2000 cubic cm per minute) minutes? Why should we say that at t = 0, there is 60,000 cubic cm of oil already leaked? t = 0 should represent the time in which oil started to leak; not the time in which the recovery device started. Whatever. I'll accept the point deduction and I understand the official reasoning, but due to stress/anxiety that is how I approached the question during test day. | |
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05-10-2008, 07:54 AM
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#87 | | Junior Member
Join Date: Mar 2008
Posts: 150
| 2b "A recovery device arrives on the scene and begins removing oil...where t is the time in minutes since the device began working."
2c "By the time the recovery device began removing oil, 60,000 cubic centimeters of oil had already leaked"
Basically, the question tells you that t=0 is when the recovery device started working. | |
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05-10-2008, 08:14 AM
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#88 | | New Member
Join Date: Mar 2008
Posts: 18
| Bleh, I didn't do too bad. Just got the two limits on 5c and 6d wrong. Hope they weren't worth too much. | |
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05-10-2008, 11:40 AM
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#89 | | New Member
Join Date: Jun 2007
Posts: 18
| does any one know if there is a calc bc thread if not lets start one | |
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05-10-2008, 12:28 PM
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#90 | | Senior Member
Join Date: May 2007 Location: Seattle--> Swarthmore '12
Posts: 2,398
| PAHreen: It really doesn't matter, but that's just how the question defined it. I think it would be okay if you solved the question using your definition of t, but you'd have to specifically state what you meant by t. But the question asks specifically for their t.
deanis15: There is. Look for it. | |
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