*Biology Paper 5 tips*

[knowitall10]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_s09_qp_5.pdf

Someone PLEASE explain me question 3, part (b) (ii) and (iii)
help will be much appreciated!

b(ii)
The standard deviation tells us hw much thw values deviate from the mean..write this and quote some fig from the table.
b(iii) is basically asking you the standard question on null hypothesis..i din't do the question..but if you still dnt get it, i'll be glad to help you

 

[Soldier313]

I haven't done this paper....i feel like a useless jerk now... =/

Dude, it's kay, you must have done many other papers, inshaAllah that should serve as enough

 

[Marks&Spencers]

Ok I'm starting to see that the alerts coming from this thread are increasing. Look people, you need to stay focused. Don't start freaking out now; this is not the time to do that, our exam is tomorrow! Don't stay up too late or you won't be able to focus properly.

hey can anyone explain me how to find E expected value in chi squared test
i know we can find by finding the mean of the observed value what is the other method
cause in nov 11 p53 question two i am not gettin the correct answer! Help!

This has been already discussed earlier in this thread. The right answer was given on page 14 of this thread. Check it out.

 

[knowitall10]

Ok I'm starting to see that the alerts coming from this thread is starting to increase. Look people, you need to stay focused. Don't start freaking out now; this is not the time to do that, our exam is tomorrow! Don't stay up too late or you won't be able to focus properly.

This has been already discussed earlier in this thread. The right answer was given on page 14 of this thread. Check it out.

Thank you!!♥

 

[Irfan1995]

For qn 1 b i of this paper, the standard deviation I calculated was 2.36, but the ms says 2.23 :/
Can someone please help?

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_y07_sp_5.pdf

Irfan1995 knowitall10
and everyone else
Thank you

You've calculated the sample standard deviation.
You're supposed to calculate the population standard deviation.
The formula for the population standard deviation is exactly the same, but the denominator is "n" instead of "n-1"
Personally, I don't think it's fair to provide you with the sample standard deviation equation and ask you to find the population standard deviation.

 

[Marks&Spencers]

Thank you!!♥

Sis, I'm the one who is supposed to be thanking you, for you have been my rock these days since I started solving paper 5. I had no notes at all, I honestly started from scratch. For the statistical tests I had the revision guide for help, but other than that, my knowledge of the experimental procedures and everything else, came from your first two posts. Thank YOU!

 

[comrade]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_s09_qp_5.pdf

Someone PLEASE explain me question 3, part (b) (ii) and (iii)
help will be much appreciated!

Standard deviation is a measure of the amount of scatter around the mean in a data set. You have to compare them I suppose. I don't know that much but I think the standard deviation is not significant here. The difference is very less for the first two pH. At 7 pH there is a significant difference.

 

[Paparazzi478]

What's your question, Sis?

it is in oct/nov p53 question 2 part b(ii) i dont know how to find the E expected value in chi squared test

 

[Marks&Spencers]

You've calculated the sample standard deviation.
You're supposed to calculate the population standard deviation.
The formula for the population standard deviation is exactly the same, but the denominator is "n" instead of "n-1"
Personally, I don't think it's fair to provide you with the sample standard deviation equation and ask you to find the population standard deviation.

Irfan1995 you're back! Alhamdulillah! I thought you went to sleep early or something. Could you please answer my questions two pages earlier I think on this thread? It's been really annoying me!

 

[comrade]

ok..for the chi squared part?

Yes that part.

 

[Soldier313]

You've calculated the sample standard deviation.
You're supposed to calculate the population standard deviation.
The formula for the population standard deviation is exactly the same, but the denominator is "n" instead of "n-1"
Personally, I don't think it's fair to provide you with the sample standard deviation equation and ask you to find the population standard deviation.

Thanx! I was just thinking why the formula was diff from the one used in stats
anyways sorry but er what exactly is the diff btwn sample and population standard devs?
Thank you so much!

EDIT: Look at the next part of the qn, the graph plotting bit, the ms says the means are 55.9 and 122. However, the means i calculated were 56.0 and 123.3!!

 

[faangelica]

plz can someone me with this question oct/nov 2009 paper 51 question 2 part a)2)

 

[sagystu]

You have to always write precautions. Just have a look at a couple of mark schemes. First you have to write about independent variable, followed by dependent variable, standardizing variables, safety and then reliability. You'll get an idea for each experiment if you go through mark schemes.

could u give me an example for a precaution or a safety certain experiment , i don't wan't to memorize i just don't understand the concept .

 

[faangelica]

could u give me an example for a precaution or a safety certain experiment , i don't wan't to memorize i just don't understand the concept .

risk might be of burning yourself while handling hot apparatus ,so use gloves thats precaution

 

[Marks&Spencers]

could u give me an example for a precaution or a safety certain experiment , i don't wan't to memorize i just don't understand the concept .

Or in experiments where leaves or pollen are collected, some people might have allergies to them, so you should cover your face with mask or handle with gloves.

 

[Marks&Spencers]

plz can someone me with this question oct/nov 2009 paper 51 question 2 part a)2)

There is no part a)2). If you mean c)(ii), the one that involves calculations, then they say at the beginning of the question that the initial no. of cells is 3000, and the final number is 6200 (which you calculated by simply adding values of the number of cells in culture then dividing by number of samples take,i.e, 10). Then you just plug in these values into the formula given

 

[faangelica]

There is no part a)2). If you mean c)(ii), the one that involves calculations, then they say at the beginning of the question that the initial no. of cells is 3000, and the final number is 6200 (which you calculated by simply adding values of the number of cells in culture then dividing by number of samples take,i.e, 10). Then you just plug in these values into the formula given

sorry its part b)

 

[faangelica]

m soo upset about this question m not able to get y we multiply and wat we multiply with 250

 

[ultraviolet]

SOMEONE PLEASE EXPLAIN THIS TO ME Q 1-b)i
http://papers.xtremepapers.com/CIE/...nd AS Level/Biology (9700)/9700_w12_qp_52.pdf

 

[biba]

*hi5* so did I... -__-

**thumbs up** me too!!!