Conditional Probability 5 • Exam Questions pt. 1 • Stats2 Ex2 ExamQ • 🚀
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- Опубликовано: 30 сен 2024
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I cant believe I got that last one right independently, thank you for being such a great teacher
What a lovely thing to say. Thank you!
Sir I was wondering how exactly do u know if u should draw a Venn diagram or a tree diagram or just use the formulas when the q doesn’t mention anything? I’m a bit confused like are there any tips or tricks please
This is an excellent question!
Here's my thinking:
1) if it's a worded, conditional question (something like 'if it rains on Monday, the probability it rains on Tuesday is 0.3, but if it doesn't rain on Monday, the probability it rains on Tuesday is 0.1) is perfect for a tree diagram. Otherwise, I tend not to like tree diagrams very much - even at GCSE I prefer to just think of the different options, rather than needing to visualise them
2) it's all P(A)=, P(AnB)=, etc. this is a prime candidate for a Venn diagram - you could just plough on using the formulae, but for me the visual aid of a Venn is really excellent to spot how to find missing values
3) the formulae should be deployed pretty much any time you see a given that | line, and definitely when looking at independence laws!
Does this help?
@@BicenMaths yess this is so helpful and thank u so much for the prompt reply, ur the best teacher ever!
If you answer these exam questions does you believe i can do these in further problems?like i will practice more but i just wanna know if i clear this topic or not
Yes these are a good indication if you understand it!
for 7:30 i completely forgot about that independent rule and did it another way. Used the P(B|C)=P(B) then, i layed it out: P(B|C)=P(BANDC)/0.2. I then subsituited P(B) to equal P(B|C) so:
0.45=P(BANDC)/0.2, then solved it. Then watched the video and realized i could have done it in an easier way
There's often shorter ways with this questions! I usually look at the number of marks to guide my thinking of how complicated I should expect it to be!
damn seeing you do the last question really made it alot easier than it seemed
ill come back in a couple days later to retry it
Great strategy - retrying questions a few days later is a fantastic learning tool.
hey sir for all probability questions, is it fine to leave answers as a fraction rather than a decimal e.g. i left it as 3/100 instead of 0.03?
Just want to make sure i dont lose that final accuracy mark!
Yes that should be fine - if in doubt, write both
P = 3/100
= 0.03
for 4:45, how would you find out not and and not be without drawing the venn diagram?
I would always recommend a Venn diagram for this exact reason! Makes it so much easier!
Sir I can't get my head around on q4 b can you break it down for if possible
Sorry for the late reply! As the students all had a sandwich and drink, we're now only looking at the S circle (as this represents those with sandwich and drink). We then need to see what proportion of them had a chocolate bar - which is 0.27/(0.33+0.27). We then multiply that by 80, to find an estimate of how many out of the 80 there are! Round it to nearest number.