MAY11 Math SL P2 TZ1

[Phil2154]

Cmon my dear friends... Let's discuss this TZ1 paper 2 of maths... Didn't like it too much... Section A generally good but section B a FAIL...

Does anyone remember any of his answers? 1st question about this triangle: I found the side 13.9cm and the angle 34.1 degrees. In the question concerning the eggs (probability) the expected value was 240*0.05? Also in the normal distribution question I think k was somewhere in the +1 s.d region and I found it to be 29.3...

[autobahn]

expected value is np, which would be 240(0.05)=12

[Phil2154]

expected value is np, which would be 240(0.05)=12

Thanks! Don't remember any of your other answers?

Also nice Sheldon pic!

[autobahn]

P(X=15)=(240 nCr 15)(0.05)^15(0.95)^225.. ended up being like 0.07? less than 10 percent for sure

the third one you had to find the probability of it being less than or equal to nine.. it was about 0.78?

[osiris]

how did everyone do on the bucket question in part B

[Phil2154]

stupid bucket.....only the first questions... show that a=4 and that stuff..

[Dennis Cowfish]

was the bucket above or below the water??

also for question 5, the 240 eggs

part c

you're trying to find... was it at least 10 being brown outta 240?

yea that one

did you have to do binomial distribution, and add up the probability from 1, 2, 3, 4 all the way to 10?

that seems like a LOT of work for just 3 marks... plus the space given is TINY

i think there has to be a shortcut...

[Summer Glau]

I hated the bucket question I think I got my t values wrong, so I don't know if the bucket was above or below the water for sure...

I think this was a weird paper 2. Usually they put long questions about statistics but there was only a short question this time! It had a long question about log/ln which was strange, I thought.

Anybody else think this paper was slightly strange?

was the bucket above or below the water??

also for question 5, the 240 eggs

part c

you're trying to find... was it at least 10 being brown out of 240?

yea that one

did you have to do binomial distribution, and add up the probability from 1, 2, 3, 4 all the way to 10?

that seems like a LOT of work for just 3 marks... plus the space given is TINY

i think there has to be a shortcut...

Yeah it was something like that. I just found the probability of brown eggs up to 9 eggs, then I did 1-(P is less than/equal to 9). For that question you could have used binomcdf on your GDC to calculate the probability.

[Emmi]

The bucket question was definitely hard. Although I did come up with two values for t, I don't know if either of them are right. For my second value of t, I plugged it into the function and the result was negative, so I'm going with "the bucket was underwater."

Yeah it was something like that. I just found the probability of brown eggs up to 9 eggs, then I did 1-(P is less than/equal to 9). For that question you could have used binomcdf on your GDC to calculate the probability.

For the eggs question, I thought it was normal distribution and got values from that....are you sure we were supposed to use binomial distribution?

[Phil2154]

The eggs was surely a binomial distribution question.... @summer glau: I found the ln question really easy since we had a calculator... Where were you stuck?

Only Americans and Canadians here right? (I mean in TZ1)

[Summer Glau]

Yeah it was something like that. I just found the probability of brown eggs up to 9 eggs, then I did 1-(P is less than/equal to 9). For that question you could have used binomcdf on your GDC to calculate the probability.

For the eggs question, I thought it was normal distribution and got values from that....are you sure we were supposed to use binomial distribution?

I didn't use normal distribution because it didn't really say that the eggs were normally distributed or anything. It just looked like a binomial question to me

@Phil2154: I got the log/ln question, I just thought it was weird that they had a long question like that

Edited May 6, 2011 by Summer Glau

[thinkpink]

I found this one very easy, especially compared to Paper 1, maybe it was just me.

The bucket was under water, the value was something around -1 (whereas the bucket was situated at y=2). So yes, it was underwater. In order to find the two values, you would have to find the derivative, graph it, and then find where y=(-0.5). I made the mistake of looking for +0.5 at first, but realized that the word "decreasing" was bolded, which means that they were looking for negative values of the derivative.

For the last question (the log one), they asked what f prime of (0) was. I found this one the trickiest because the answer (to the best of my knowledge) is non-existent. The log graph they gave us had an asymptote at x=0, therefore there is no derivative at x=0.

I remember my answers to the other questions as well, and if you want any specific questions just ask me! One answer on the top of my head... the one with the defective/non defective... answers were 0.84 and 0.7 (0.84 for expected value and 0.7 for the value of B if they wanted to raise the expected value to 0.87)

Yeah it was something like that. I just found the probability of brown eggs up to 9 eggs, then I did 1-(P is less than/equal to 9). For that question you could have used binomcdf on your GDC to calculate the probability.

For the eggs question, I thought it was normal distribution and got values from that....are you sure we were supposed to use binomial distribution?

I didn't use normal distribution because it didn't really say that the eggs were normally distributed or anything. It just looked like a binomial question to me Maybe you could use normal distribution though.

The eggs question was a binomial distribution because there are only two outcomes (either egg is brown or egg isn't brown). So if you did it on your GDC as I did... it would be binompdf(240, 0.05, n). For the second part you would use 1 - binomcdf(240, 0.05, 9)

[IBSurvivalNum93]

The last question wasn't f prime it was the inverse of f which was really simple. Perhaps it was a bit hard if you used the log form but finding the inverse with the ln form was really easy it was 3^x/2. So the answer was 1/2. In general I found paper 2 much easier than paper 1. I did make some stupid mistakes on paper 2 though. Like the reflection in the x axis on (Head banging on this one for a while...)

[thinkpink]

The last question wasn't f prime it was the inverse of f which was really simple. Perhaps it was a bit hard if you used the log form but finding the inverse with the ln form was really easy it was 3^x/2. So the answer was 1/2. In general I found paper 2 much easier than paper 1. I did make some stupid mistakes on paper 2 though. Like the reflection in the x axis on (Head banging on this one for a while...)

It was asking for inverse? Oh gosh I always miss the inverse cause it looks just like the derivative! Wait, so did they ask us to graph derivative of f or inverse of f? AH... I graphed & looked for derivative the whole time :'(

[IBSurvivalNum93]

The last question wasn't f prime it was the inverse of f which was really simple. Perhaps it was a bit hard if you used the log form but finding the inverse with the ln form was really easy it was 3^x/2. So the answer was 1/2. In general I found paper 2 much easier than paper 1. I did make some stupid mistakes on paper 2 though. Like the reflection in the x axis on (Head banging on this one for a while...)

It was asking for inverse? Oh gosh I always miss the inverse cause it looks just like the derivative! Wait, so did they ask us to graph derivative of f or inverse of f? AH... I graphed & looked for derivative the whole time :'(

We had to graph the inverse as well. So graphing ln2x/ln3 and 3^x/2. As well as indicating some point on the graph clearly.

[thinkpink]

The last question wasn't f prime it was the inverse of f which was really simple. Perhaps it was a bit hard if you used the log form but finding the inverse with the ln form was really easy it was 3^x/2. So the answer was 1/2. In general I found paper 2 much easier than paper 1. I did make some stupid mistakes on paper 2 though. Like the reflection in the x axis on (Head banging on this one for a while...)

It was asking for inverse? Oh gosh I always miss the inverse cause it looks just like the derivative! Wait, so did they ask us to graph derivative of f or inverse of f? AH... I graphed & looked for derivative the whole time :'(

We had to graph the inverse as well. So graphing ln2x/ln3 and 3^x/2. As well as indicating some point on the graph clearly.

WOW *FREAKS OUT* Are you SURE? Does anybody else remember? All my friends (myself included) thought it was derivative! We all did derivative! We're all freaking out now! (Calling them)

[IBSurvivalNum93]

Yah, I'm pretty sure it was f^-1.

[Emmi]

The eggs was surely a binomial distribution question.... @summer glau: I found the ln question really easy since we had a calculator... Where were you stuck?

Only Americans and Canadians here right? (I mean in TZ1)

I hate my life

[harvard123]

yupp, it was def inverse.

and also, in the probability/stats question, it was asking about the chance of greater than 10 eggs being brown right?

[mathlete94]

Going back to the bucket question (stupid bucket!!) since t was supposed to be time, time cant be negative, so would the answer be not underwater because the other value for t gave us a positive number? By the way, how were you supposed to know which value was the second one?

I also thought the second test was much easier than the first test. I was so frustrated on the first test because i to tally forgot E(X)!!! And we had done a similar question the day before as practice!!! Oh well, that one was only two points anyways.

Does anyone know what the score range is to get a 7?