AP Calculus AB 2015 Thread

did anyone get -1/64 for one of them?

@kajay88 What was the question asking?

@nhljohn871 i got 16/9 too

@Eggyolk the answer to the mx+b one was m=1 and b=1 if you had form o

For the R and D FRQ, wouldn’t you have to add the value at 8hrs to the integrals instead of initial?

Wasn’t the answer to the derivative of the inverse question 1/6?

@Eggyolk k it was the question some one got 1/32 for

yeah @mochilate1897

@KaiserEric13 for which part of the question? the final part where they ask for an equation for w?

@kajay88 I don’t remember that specific question. Also for the y = mx + b question, see dogeater’s explanation in the previous page… it is pretty convincing.

@Eggyolk Yeah I believe so

And did you guys get Neither for that one dreadful FRQ?

@KaiserEric13

For t>8, the rates still applied right? There is no difference between the rates before t = 8 and after t = 8 right? I can’t really remember.

But you had to find the time when the total amount of water in the pipe is equal to 50 (when it starts to overflow).

so it was 30 + integral of (R(t) - D(t)) from 0 to w = 50 .

So Integral from 0 to w of [R(t) - D(t)] = 20

@mochilate1897 the question where they asked if there was a max or min at a certain point? I put neither because it wasn’t even a critical point of f ’

@Eggyolk couldn’t you do integral 8 to w

@eggyolk yes i put the same, just that it wasn’t equal to zero. Would they accept that reasoning?

Also I feel like i missed nearly all the credit for c and d of 3-4 of the FRQs, what would i be looking at in terms of a score?

@KaiserEric13 you would have to put the total amount of water at t= 8 if you did that, then you should be fine.

but to find the value at t= 8 would need to do " 30 + the integral from 0 to 8 of R(t)-D(t)" and then you would add that value to the “integral from 8 to w of R(t) - D(t)”

@mochilate1897 I just made sure that I got credit for the question by saying that mins and maxes only happen at critical therefore there is no min/max at that point. I think it depends on the way you phrased it.

I’m not really experienced with the scores. but I think you would still be able to get a 5 depending on how well you did on the MC and depending on the weight of c and d in both of these questions.

I’m just hoping that there isn’t a lot of weight on 4d.

@Eggyolk OK I did that so I should be Gucci thx :^)

Also sorry for repeating previously asked questions but what about RRAM from FRQ? 8000ish?

@KaiserEric13 No problem ;D.

Also does anybody know if you can just put R(t) instead of the entire function because I wasted time by writing the entire function.

i think I got 11000ish not sure… What was the process that you did?

i remember I got 11200 as an answer for a problem not sure if this is the question you’re talking about.

what did you guys get for that H(t) problem

@Eggyolk Drew lines from the points over to the left starting with second point and added up the areas. Honestly I’ve seen like 4 plausible answers for this question…

@mochilate1897 H(t) was the difference in rate between R(t) and D(t)? what did we need to find?

@KaiserEric13 Did you multiply each value by its width? because the width was not the same for all the intervals.

What I did was get the difference in x-value between the first two points provided and multiplied that by the f(x) value of the second point. So I was multiplying the width of the Rectangle by the y-value of the second point.