Edexcel A-level Biology B Paper 3 (9BI0 03) - 21st June 2023 [Exam Chat]

Can someone please help me with the chi squared calculations? How do I work it out?

so u are given the observed values. u have to find the expected via using the ratio. add the ratio and do the total observed/total ratio. then multiply this to the separate ratios to get ur expected values.do observed - expected and square this then then divide this by the expected. do this for how many values there is and add the numbers to get you chi squared value. then compare this to ur critical vale. if critical value is greater then accept null hypothesise and say there is no sig difference between observed and expected and that and difference is due to greater then 5 percent chance

Reply 21

ifif4

13

Original post by ramzan11111

so u are given the observed values. u have to find the expected via using the ratio. add the ratio and do the total observed/total ratio. then multiply this to the separate ratios to get ur expected values.do observed - expected and square this then then divide this by the expected. do this for how many values there is and add the numbers to get you chi squared value. then compare this to ur critical vale. if critical value is greater then accept null hypothesise and say there is no sig difference between observed and expected and that and difference is due to greater then 5 percent chance

thank you so much

Reply 22

aysha0520

3

Original post by ifif4

Can someone please help me with the chi squared calculations? How do I work it out?

heres my notes on chi squared stuff

Screenshot 2023-06-19 at 23.19.35.png311.6KB

Reply 23

ifif4

13

Original post by aysha0520

heres my notes on chi squared stuff

Thank you

(edited 10 months ago)

Reply 24

epoch.ly

9

Original post by sylkiebot

Guys can someone please help me with these questions?

for eyepiece graticule i think u can count the number of tiny divisionswhich is 90 (9 divisions between 0-50), total in the circle equals the diameter of the heart

Reply 25

Idkbroo

13

Original post by epoch.ly

guys i need advice asap, i left paper 3 past papers until too late, i mean i like to think i have okay background knowledge but my exam technique needs refining. should i give up attempting past papers first, and do flashcards by going straight to mark scheme answers instead, or attempt the past papers first and then mark them. i am quite short on time and i think the flashcard method would be fastest but what do u think would be more effective

I’m literally on the same exact page as u and I was disappointed to see no one has replied 😞😞 I have no idea what to do

Reply 26

epoch.ly

9

Original post by Idkbroo

I’m literally on the same exact page as u and I was disappointed to see no one has replied 😞😞 I have no idea what to do

asked my friend, they suggested to do the papers and as much as u can then mark bc youre more likely to remember the answers. i can attest to that in previous cases so i decided to do that. make sure to really absorb the answers. if u dont have time try to do 2 today, wake up early, 2 tomorrow, prioritise 2017,2018,2019,2021 bc 2020 is presumably easier

Reply 27

aysha0520

3

Original post by epoch.ly

guys i need advice asap, i left paper 3 past papers until too late, i mean i like to think i have okay background knowledge but my exam technique needs refining. should i give up attempting past papers first, and do flashcards by going straight to mark scheme answers instead, or attempt the past papers first and then mark them. i am quite short on time and i think the flashcard method would be fastest but what do u think would be more effective

or if ur rly rly short on time then do the past papers with the mark scheme open so u understand how they want u to answer certain stuff

Reply 28

epoch.ly

9

Original post by aysha0520

or if ur rly rly short on time then do the past papers with the mark scheme open so u understand how they want u to answer certain stuff

this is a good idea - i tried it for maths but havent thought of it for bio - thanks!

Reply 29

tepij6020

any predictions for topics that may come up that havent come up on the first two papers?

Reply 30

Idkbroo

13

Original post by epoch.ly

asked my friend, they suggested to do the papers and as much as u can then mark bc youre more likely to remember the answers. i can attest to that in previous cases so i decided to do that. make sure to really absorb the answers. if u dont have time try to do 2 today, wake up early, 2 tomorrow, prioritise 2017,2018,2019,2021 bc 2020 is presumably easier

I will marry u thabks sm

Reply 31

dougjudy

1

any thoughts on topic likely to come up

Reply 32

basicacid

2

Good luck, I'm going to revise the structure of a nephron

Reply 33

pH092

7

Guys, how did you find the exam?

OP

Hey everyone :smile:

How did you find the exam?

A-level Biology

Reply 35

KillSwitch12

6

what was the devise as experiment which proves water comes from oxygen and not CO2?

Reply 36

thatonechemist

2

Original post by KillSwitch12

what was the devise as experiment which proves water comes from oxygen and not CO2?

Hill reaction

Reply 37

fegbird

2

Original post by KillSwitch12

what was the devise as experiment which proves water comes from oxygen and not CO2?

i think you're on the wrong thread, this is biology b

Reply 38

basicacid

2

What did y'all get for the maths:
3.11 mm for the scale measurement for the lung vessel
21 for the degrees of freedom
around 7.6 for the t value
around 3.5 for the bees question
glad it's over
also that graph area was really tiny.