Original post by CTinTin14
Please help!
I am on January 2011 paper, and stuck on question 4.
Please Please help me! Help me how to do it and work out too.
Thank you!!
I am on January 2011 paper, and stuck on question 4.
Please Please help me! Help me how to do it and work out too.
Thank you!!
It has a few parts - are there any in particular that you are stuck on?
Think about what distribution you can use, what it's parameter(s) are and how you can express the inequalities carefully.
Original post by SeanFM
It has a few parts - are there any in particular that you are stuck on?
Think about what distribution you can use, what it's parameter(s) are and how you can express the inequalities carefully.
Think about what distribution you can use, what it's parameter(s) are and how you can express the inequalities carefully.
I am stuck on all of them
Original post by CTinTin14
I am stuck on all of them
Okey dokey, we'll figure this out
From the information in the question what do you think the distribution of how many targets he hits is?
Original post by SeanFM
Okey dokey, we'll figure this out
From the information in the question what do you think the distribution of how many targets he hits is?
From the information in the question what do you think the distribution of how many targets he hits is?
says: at most 5 targets
Original post by CTinTin14
says: at most 5 targets
Yes, that's part a) of the question, but it may help to figure out what your starting point is for answering that question.
Can you think of the different distributions that you've learned in S1? (I'm not sure which ones AQA covers but some examples of distributions are Poisson, Binomial, Normal, Exponential).
Think of those, and think of which one suits the question (you'll probably see a list of conditions for each distribution you've come across), and then think of the parameters of the distribution (eg if it was Normal, then you'd need the mean and variance - but it's not and you don't need these things).
Original post by SeanFM
Yes, that's part a) of the question, but it may help to figure out what your starting point is for answering that question.
Can you think of the different distributions that you've learned in S1? (I'm not sure which ones AQA covers but some examples of distributions are Poisson, Binomial, Normal, Exponential).
Think of those, and think of which one suits the question (you'll probably see a list of conditions for each distribution you've come across), and then think of the parameters of the distribution (eg if it was Normal, then you'd need the mean and variance - but it's not and you don't need these things).
Can you think of the different distributions that you've learned in S1? (I'm not sure which ones AQA covers but some examples of distributions are Poisson, Binomial, Normal, Exponential).
Think of those, and think of which one suits the question (you'll probably see a list of conditions for each distribution you've come across), and then think of the parameters of the distribution (eg if it was Normal, then you'd need the mean and variance - but it's not and you don't need these things).
Binomial Distribution
Original post by CTinTin14
Binomial Distribution
Well done
that's correct.So what are the parameters? (the values of n and p).
So how will you find the probability of him hitting 'at most 5 targets'? How can this be written as an inequality for you to be able to read it off the tables?
Original post by SeanFM
Well done that's correct.
So what are the parameters? (the values of n and p).
So how will you find the probability of him hitting 'at most 5 targets'? How can this be written as an inequality for you to be able to read it off the tables?
that's correct.So what are the parameters? (the values of n and p).
So how will you find the probability of him hitting 'at most 5 targets'? How can this be written as an inequality for you to be able to read it off the tables?
(15,0.45)
i) 0.2608
ii)0.025
iii) 0.4522-0.2608=0.1914
How do you do iv?
Original post by CTinTin14
(15,0.45)
i) 0.2608
ii)0.025
iii) 0.4522-0.2608=0.1914
How do you do iv?
i) 0.2608
ii)0.025
iii) 0.4522-0.2608=0.1914
How do you do iv?
I'll assume you've done them correctly, so you know how to write the inequalties correctly.
How do you write at least 5 and at most 10 as an inequality? Hence how do you find the probability?
Original post by SeanFM
I'll assume you've done them correctly, so you know how to write the inequalties correctly.
How do you write at least 5 and at most 10 as an inequality? Hence how do you find the probability?
How do you write at least 5 and at most 10 as an inequality? Hence how do you find the probability?
P(5<R<10) similar right? but i don't know what to do next
Original post by CTinTin14
P(5<R<10) similar right? but i don't know what to do next
Yes, assuming the < signs are the 'less than/greater than or equal to signs.'
So you could easily read off P(X≤10), but that would leave you with the bits below 5 added on when you don't want them. So what needs to be taken away from P(X≤10) to only have the things that are greater than or equal to 5?
Original post by SeanFM
Yes, assuming the < signs are the 'less than/greater than or equal to signs.'
So you could easily read off P(X≤10), but that would leave you with the bits below 5 added on when you don't want them. So what needs to be taken away from P(X≤10) to only have the things that are greater than or equal to 5?
So you could easily read off P(X≤10), but that would leave you with the bits below 5 added on when you don't want them. So what needs to be taken away from P(X≤10) to only have the things that are greater than or equal to 5?
0.2608 and 0.9745
so you do 0.9745-0.2608=0.8541
(edited 8 years ago)
Original post by CTinTin14
0.2608 and 0.9745
so you do 0.9745-0.2608=0.8541
so you do 0.9745-0.2608=0.8541
Almost
It would help if you wrote down all of your working before plugging in the numbers.
You've done P(X≤10) - P(X≤5), which takes away the probability of anything being 5 or less, which is almost right, but we want to keep the things that are =5 because it says at least 5.
So knowing that, for what value of k do you take away P(X≤k) from P(X≤10) to get P(5≤X≤10)? What values don't you want from the range 0 to 10?
Original post by SeanFM
Almost
It would help if you wrote down all of your working before plugging in the numbers.
You've done P(X≤10) - P(X≤5), which takes away the probability of anything being 5 or less, which is almost right, but we want to keep the things that are =5 because it says at least 5.
So knowing that, for what value of k do you take away P(X≤k) from P(X≤10) to get P(5≤X≤10)? What values don't you want from the range 0 to 10?
It would help if you wrote down all of your working before plugging in the numbers.
You've done P(X≤10) - P(X≤5), which takes away the probability of anything being 5 or less, which is almost right, but we want to keep the things that are =5 because it says at least 5.
So knowing that, for what value of k do you take away P(X≤k) from P(X≤10) to get P(5≤X≤10)? What values don't you want from the range 0 to 10?
so is it 0.853 to 0.855?
Original post by CTinTin14
so is it 0.853 to 0.855?
Yes. Though I noticed that your previous calculation doesn't equal what it's supposed to.
Looking at the mark scheme the method I was hinting at is there. P(X≤10) - P(X≤4) (as you have the probability of things beings 10 or less, and if you take away the probability of things being 4 or less you are left with the probability of things that are between 5 and 10 (including 5 and 10). So, reading from the tables,
P(X≤10) is 0.9745 and P(X≤4) is 0.1204, so you do as they've done to get something between 0.853 and 0.855. If you don't understand this method let me know. I am happy to explain things again and/or slowly.
I do not understand the values after 'or' though.
(edited 8 years ago)
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