# Edexcel IAL Maths S2 24, june 2019

#1
Hey guys this thread is for S2
0
2 years ago
#2
hey, how do we exactly solve the hypothesis questions i just don't understand it,
like i know the terms and all but don't know how to like apply it in the question
plz help
0
#3
Let's see....
First, you have to figure out the distribution- binomial or poisson
then you start writing ur hypothesis- make sure to write this bit it is worth marks
you first write the null hypothesis which is always = >>>>H0: P=(the probability you have)
then the alternative hypothesis H1: p > or < or no equal to the probability you have
you know what o put from the question if it sais increase you put >
decrease put <
if they want to see if there was any change put not equal

I encourage u to watch videos tho,, this explanation is nowhere near enough
(Original post by mushriqite)
hey, how do we exactly solve the hypothesis questions i just don't understand it,
like i know the terms and all but don't know how to like apply it in the question
plz help
0
2 years ago
#4
(Original post by IGCSEsurvivor)
Let's see....
First, you have to figure out the distribution- binomial or poisson
then you start writing ur hypothesis- make sure to write this bit it is worth marks
you first write the null hypothesis which is always = >>>>H0: P=(the probability you have)
then the alternative hypothesis H1: p > or < or no equal to the probability you have
you know what o put from the question if it sais increase you put >
decrease put <
if they want to see if there was any change put not equal

I encourage u to watch videos tho,, this explanation is nowhere near enough
okay so here i did a question from past paper just the a part and here i dont understand is how will i make the conclusion out of it like p of customer buying is greater than the critical value so what will i reject it H0 or keep it or what

0
2 years ago
#5
hey guys can someone pls upload jan 2019 s2 mark scheme?
0
2 years ago
#6

(Original post by Black&Whitee)
hey guys can someone pls upload jan 2019 s2 mark scheme?
0
#7
if the probability you found was greater than the actual significant level you DON'T reject H0 and say "because the value is not significant so we do not reject H0)

IF p was smaller than the actual significant level then you DO reject H0
(Original post by mushriqite)
okay so here i did a question from past paper just the a part and here i dont understand is how will i make the conclusion out of it like p of customer buying is greater than the critical value so what will i reject it H0 or keep it or what

1
2 years ago
#8
(Original post by Black&Whitee)
hey guys can someone pls upload jan 2019 s2 mark scheme?
1
2 years ago
#9
which year is this?
(Original post by mushriqite)
okay so here i did a question from past paper just the a part and here i dont understand is how will i make the conclusion out of it like p of customer buying is greater than the critical value so what will i reject it H0 or keep it or what

0
2 years ago
#10
(Original post by tanupatel)
which year is this?
june 2011
0
2 years ago
#11
hey... okay so you reject H0 when the probability is in the CR. This means when it is less than the significance level.
and accept H0 when the probability is greater than the significance level. In this case for part a, you have found the probability to be 0.0480>0.025. so you accept H0 and say that there was no change.
however if the probability was let's say 0.023 which means it is less that 0.025 you will reject H0 and say that there was a change in the proportion of customers buying from next to the till.

I hope you understand
(Original post by mushriqite)
okay so here i did a question from past paper just the a part and here i dont understand is how will i make the conclusion out of it like p of customer buying is greater than the critical value so what will i reject it H0 or keep it or what

1
2 years ago
#12
Nice thread but I'm wondering, if the question asked you to do a 2-tailed test where the Alternative Hypothesis doesn't equal the Null Hypothesis probability [Say if H0: p = 0.35 & H1: p ≠ 0.35]

And the question gave you a binomial distribution [Say, X ~ B(50, 0.35)] and told you that out 50 people, only 30 partook this test or anything really.

Do you do, P(X ≤ 30 | p =0.35) & find the probability whether it's greater or lower than significance level or do you do, P(X ≥ 30 | p =0.35) and do the rest?

Or do you find Critical Region and go from there whether or not to reject the Null Hypothesis?

Thanks!
0
2 years ago
#13
any predictions on the difficulty of tomorrow’s paper?
0
2 years ago
#14
2019 Jan paper was kinda different so I dunno, maybe they'd try to opt for something different this time around too? Expect 1 or 2 things "different" this time around too and you're most likely gonna be fine.

However, I'd advise you guys to revise the "percentage points" in S1 page 179 & the "skew distribution" in page 67 as these stuff come up quite often in my experience. Also, if the question has the keyword "given" then you should do a conditional probability etc

Hope you guys do well in tomorrow's exam!
(Original post by Christiana24)
any predictions on the difficulty of tomorrow’s paper?
Last edited by mechguffin; 2 years ago
1
2 years ago
#15
Hi i'm gonna answer this to the best of my ability:

Lets set it out like you've described:
H0: p = 0.35
H1: p ≠ 0.35
at the 5% significance level (for example)

for X ~ B(50, 0.35)

You can do it either way, but the significance level must be halved in both; so in this case the significance level would be 0.025 or 2.5%. Since this is a two tailed test, you have to consider both an increase AND a decrease in the parameter.

Using the critical region method (i prefer this way):
P(X≤C1) < 0.025
and P(X≥C2)<0.025

where X≤C1 and X≥C2 are the critical regions.

you would solve for C1 and C2 from there using tables!

If the 30 lies outside the critical region, then H0 is not rejected... yadda yadda

Hope this helps
(Original post by mechguffin)
Nice thread but I'm wondering, if the question asked you to do a 2-tailed test where the Alternative Hypothesis doesn't equal the Null Hypothesis probability [Say if H0: p = 0.35 & H1: p ≠ 0.35]

And the question gave you a binomial distribution [Say, X ~ B(50, 0.35)] and told you that out 50 people, only 30 partook this test or anything really.

Do you do, P(X ≤ 30 | p =0.35) & find the probability whether it's greater or lower than significance level or do you do, P(X ≥ 30 | p =0.35) and do the rest?

Or do you find Critical Region and go from there whether or not to reject the Null Hypothesis?

Thanks!
1
2 years ago
#16
Nice! I also prefer the critical region method for a two-tailed tests such as these as it reduces the confusion of whether to take P(X ≤ 30) or P(X ≥ 30) in this case.
(Original post by JMroueh)
Hi i'm gonna answer this to the best of my ability:

Lets set it out like you've described:
H0: p = 0.35
H1: p ≠ 0.35
at the 5% significance level (for example)

for X ~ B(50, 0.35)

You can do it either way, but the significance level must be halved in both; so in this case the significance level would be 0.025 or 2.5%. Since this is a two tailed test, you have to consider both an increase AND a decrease in the parameter.

Using the critical region method (i prefer this way):
P(X≤C1) < 0.025
and P(X≥C2)<0.025

where X≤C1 and X≥C2 are the critical regions.

you would solve for C1 and C2 from there using tables!

If the 30 lies outside the critical region, then H0 is not rejected... yadda yadda

Hope this helps
1
#17
can someone pls help me with this

The teachers believe that the sample in the original survey was biased and claim that only 25% of the parents are in support of the new curriculum. A second random sample, of size 2n, is taken and exactly half of this sample supports the new curriculum. A test is carried out at a 10% level of significance of the teachers’ belief using this sample of size 2n Using the hypotheses H0 : p = 0.25 and H1 : p bigger than 0.25

(d) find the minimum value of n for which the outcome of the test is that the teachers’ belief is rejected.
0
2 years ago
#18
Out of 2n people, half of them (i.e "n" people) supports the new curriculum & H1: p > 0.25 and significance level is 10%
X~B (2n, 0.25)
So now, we just do a systematic table search with P(X ≥ n) ≤ 0.1

If we let "2n" be 8, then P(X ≥ 4) = 11.38% ----> which is bigger than 10% so we can't take it
If we let "2n" be 10, then P(X ≥ 5) = 7.81% -----> which is smaller than 10% and also the closest to it!

So, 2n = 10 ----> n = 5

Basically, just do a table search after setting up the inequality.

Hope it helps
(Original post by IGCSEsurvivor)
can someone pls help me with this

The teachers believe that the sample in the original survey was biased and claim that only 25% of the parents are in support of the new curriculum. A second random sample, of size 2n, is taken and exactly half of this sample supports the new curriculum. A test is carried out at a 10% level of significance of the teachers’ belief using this sample of size 2n Using the hypotheses H0 : p = 0.25 and H1 : p bigger than 0.25

(d) find the minimum value of n for which the outcome of the test is that the teachers’ belief is rejected.
0
#19
thank you
(Original post by mechguffin)
Out of 2n people, half of them (i.e "n" people) supports the new curriculum & H1: p > 0.25 and significance level is 10%
X~B (2n, 0.25)
So now, we just do a systematic table search with P(X ≥ n) ≤ 0.1

If we let "2n" be 8, then P(X ≥ 4) = 11.38% ----> which is bigger than 10% so we can't take it
If we let "2n" be 10, then P(X ≥ 5) = 7.81% -----> which is smaller than 10% and also the closest to it!

So, 2n = 10 ----> n = 5

Basically, just do a table search after setting up the inequality.

Hope it helps
0
2 years ago
#20
How'd everyone find that?
0
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