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No problem 👍

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When we use inference (build confidence intervals and perform significance tests), we do not know what our population proportion (in this case the difference between two population proportions) is; therefore, we rely on estimates for our standard deviation assuming the proportions from our sample get us close enough to the unknown population proportions and call the modified calculation standard error. Even within the formulas for AP Statistics, the standardized test statistic is determined by: (statistic - parameter)/standard error of statistic In "perfect" situations, we do compute z-scores with the formula you mentioned. In these idealized situations, we know the population parameters (mean and standard deviation or population proportion). When performing inference, we do not know these measures which is why we use standard error in place of standard deviation. Hope this helps and good luck!

Nice work! I'm sorry you didn't know it was unnecessary.

Do any and all practice problems that your teacher suggests. I got a C in AP Calc AB my senior year of high school because I treated it like any other math class I'd taken and I hadn't really needed to try very hard to succeed in those earlier math courses. Work hard and it's not too bad.

@@tomcochranlifeisapiway Thanks, that’s good to know. Not gonna lie I kind of felt that way while taking AP Mechanics, but now I kind of regret it. Scores coming up in a couple of months.

Good luck!

how was FRQ 4-6??

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Glad you like them!

Yes. I apparently fat fingered something with the calculator entry. Sorry about that.

Correct. I just try to use them for consistency since you don't always have a situation like this one.

Nice work!

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No problem!

Should have 1-3 done and posted by the end of the day on Monday.

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You'll likely get at least "Partially Correct" and if you label the details of each value for your calculator input may earn "Essentially Correct".

Oh its just ncdf

Glad you got it figured out and sorry I couldn't respond earlier!

Glad it helped! Good luck!

You're correct. Good catch. I said verbally you'd double the calculation to determine the p-value but definitely did not have that accounted for within the work shown on the screen.

Good catch. I probably should have said the median is "approximately 11" or said it's between 11 and 12 like you've suggested.

ohhhhh nvm i get it

The sum of all of the probabilities of all possible outcomes must equal 1. Since there's one outcome we don't know, we must subtract all the known probabilities from 1 to determine the missing probability.

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Thank you. Glad to have helped and good luck if you're taking the exam in 10 days!

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Yes. I am going to try to redo this video at some point in the next few days. I published this about 6 months ahead of the scoring guidelines being released so didn't really have a way to truly check my answers. I most definitely should have used a z-score in part b due to having access to the population standard deviation. I also misinterpreted the first part of part d. Look for an updated video soon. E, P, E, P = 3/4 for me on this one : (

The process for finding this is explained near the 9:30 mark

Make that 9:15

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This may be the nicest thing anyone's ever said to me.

Most welcome 😊

Glad I could help!

The issue of increasing/decreasing functions comes down to comparing y-values their graphs with other y-values near them. A function is decreasing when y-values get smaller as x-values increase. Due to the negative slope of g(x) just after x=0, g(0) will be a larger y-value than any y-value found on the graph for x-values above x=0. This outcome when we compare y-values is what allows for us to include x=0 within the interval of decrease. Think of the graph of f(x)=x^3. x=0 is a critical number for the function since 3x^2=0 when x=0. On the graph, the point (0,0) is above any point immediately to its left and below any point immediately to its right. This function is increasing on (-infinity, infinity) even though the derivative is equal to 0 at x=0. If you're specifically getting ready for the AP exam, each of the following should receive credit for part c: (0,5), (0,5], [0,5] since the graders realize different textbooks and/or teachers may use slightly different conventions for handling intervals of increase/decrease.

I may know how that happened...

@@tomcochranlifeisapiway willing to explain???????🤔

I'm guessing most AP calculus teachers use this worksheet

@@tomcochranlifeisapiway I'm from Australia...any idea?... i'm just guessing it may be a globally shared worksheet

Yes. I would assume that's the case.

If the task was to find f(g(3)), then you'd do exactly what you said. Since the task is "find the derivative of f(g(x)) at x=3," we need to find the derivative of f(g(x)) prior to evaluating at x=3.

Thank you@@tomcochranlifeisapiway

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You're welcome!

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Correct. The calculator problems they place on the exam each year will typically involve solving an equation graphically with the calculator at some point.

Happy to help!

If there are other arguments you can make to eliminate a location as the potential absolute minimum, which is the case in this situation, you can explicitly state why you're ruling a location out as the potential answer. You can also find the value of the function at each location using area arguments similar to the ones I used to determine the function value at x=-2. If there wasn't evidence indicating the other candidates were not able to be the absolute minimum, that is exactly what I would have needed to do to receive the maximum amount of points from the graders.

Since there are 429 data points within this set, the median should be at the halfway point of the data if the data is placed into order. 429/2 allows for us to pinpoint how many values are before and after the median.

Xd

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