The Edexcel S1 (18/05/12 - AM) Revision Thread

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Reply 200

otrivine

Original post by chignesh10

the grade boundary was 62 for jan 06, ok? capiche?

oh i get it so i scraped an A
but was the paper hard from your opinion

Reply 201

dslc

Original post by otrivine

oh i get it so i scraped an A
but was the paper hard from your opinion

Jun-05 53
Jun-01 55
Nov-03 55
Jun-10 55
Jan-05 56
Jan-01 57
Jun-04 57
Nov-04 57
Jan-09 57
Nov-02 58
Jun-07 58
Jun-06 59
Jan-11 59
Jan-04 60
Jun-08 60
Jun-09 60
Jan-12 60
Jan-07 61
Jun-11 61
Jun-03 62
Jan-06 62
Jan-08 63
Jan-10 65

These are ordered by the raw marks required to gain an A.
The higher the number, the easier the paper.

Reply 202

otrivine

Original post by dslc

thanks and one more question u know the examination paper question on the edexcel book the last question on part c) i got 0.375 but book is getting 0.276 ?

Reply 203

dslc

Original post by otrivine

thanks and one more question u know the examination paper question on the edexcel book the last question on part c) i got 0.375 but book is getting 0.276 ?

Is this the question about Jean and hitting the target?

Reply 204

Scorcher

Can anyone help me with 2b. It's from Jan 2012 I have attached the question below.

So far I have:

P(A u B) = P(A) + P(B) - P(A n B)
2/3 = 1/4 + P(B) - 1/4*P(B)
5/12 = P(B) - 1/4*P(B)

I have checked the mark scheme and I am correct up to this point but I am stumped on what to do next. The mark scheme jumps to:

5/12 = 3/4*P(B)

But I have no idea how P(B) - 1/4*P(B) gets to 3/4*P(B).

The answer is probably a really simple one, but if anyone can help me it would be much appreciated :smile:

Reply 205

knowledgecorruptz

Original post by Scorcher

Can anyone help me with 2b. It's from Jan 2012 I have attached the question below.

Replace P(B) with "x". You now have x - 1/4*x - in other words 1x - 0.25x, which makes 0.75x, which = 3/4x.

x = P(B), therefore, P(B) - 1/4*P(B) = 3/4*P(B) :smile:

P(B) = 5/9...i hope :wink:

(edited 11 years ago)

Reply 206

Scorcher

Original post by knowledgecorruptz

Replace P(B) with "x". You now have x - 1/4*x - in other words 1x - 0.25x, which makes 0.75x, which = 3/4x.

x = P(B), therefore, P(B) - 1/4*P(B) = 3/4*P(B) :smile:

P(B) = 5/9...i hope :wink:

You life saver! How the hell did I not get that :confused:

Thanks for the explanation, much appreciated :smile:

Reply 207

stuck18

Original post by QwertyG

wow. when did you start past papers for s1??

about 2 weeks ago. kinda regretting doing all of them so quickly cos now im close the exam.. im sort of struggling of what to do .. i dont want to not revise for s1 any more cos u cant over-revise for any subject. so any tips or links for probability questions?

Reply 208

QwertyG

Original post by stuck18

wtf 2 weeks and you done all the solomon papers/2001-2011 past papers no way lol

I cant think of anymore resources lol

Reply 209

stuck18

Original post by QwertyG

wtf 2 weeks and you done all the solomon papers/2001-2011 past papers no way lol

I cant think of anymore resources lol

yes way. it is possible when you do all nighters and only concentrate on s1 .. since this is my first exam. still SO scared for this exam. dont feel good about it :frown:

Reply 210

stuck18

Original post by Zhy

I hope there will be lots of definition questions, conditional probability, and 8-circle Venn diagrams. It will make it fun! :smile:

oh btw what do you mean by 8-circle Venn diagrams. the only ones I am aware of are the 3 circles that intersect eachother within the sample space and the standard 2 circled venn diagrams. i cant find anything to do with 8-circle ones on google or in the text book.

Reply 211

bong

Original post by stuck18

Wtf? 8 circles? thats nuts!

lawl he trolling

8 circles

! New Venn diagram has just been brought to life.
Anyways can some one please explain to me Jan 12 last question part b.
If I remember correctly it was P(232<W<w)=0.2
and you had to find w given.
(232,5^2)
Cheers

Reply 214

dslc

Original post by dan94adibi

Anyways can some one please explain to me Jan 12 last question part b.
If I remember correctly it was P(232<W<w)=0.2
and you had to find w given.
(232,5^2)
Cheers

(b) You are given P(232 < W < w) = 0.2 and W~N(232,5²) - the latter being composed from the information at the start of the question.
First of all you need to turn the normal distribution you are given into a standard normal distribution.

This step is as follows: P[(232-232)÷5 < Z < (w-232)÷5] = 0.2
Therefore: P[0 < Z < (w-232)÷5] = 0.2

Next you need to draw your normal distribution curve. You know that 0 will be at the mean, so the region must be between the middle of the normal distribution curve and some point to the right of it (w-232)÷5.

We know everything to the left of 0 has a probability of 0.5, so P[Z<(w-232)÷5] = 0.7. We can look this up in the table of probabilities to find that (w-232)÷5 ≈ 0.52.

And so, we reach: (w-232)÷5 = 0.52.
Therefore, (w-232) = 2.6
And so, w = 234.6.

In the mark scheme you will see answers are accepted so long as they round to 235

Reply 215

QwertyG

Does anyone use normal distribution on their calculator to work out ND questions??

Reply 216

shumen9523

Original post by stuck18

yes way. it is possible when you do all nighters and only concentrate on s1 .. since this is my first exam. still SO scared for this exam. dont feel good about it :frown:

Don't worry, just relax and recheck all of the papers you've solved to know exactly how and why you made the mistakes you did (or you can resolve them if you have enough time). It might be a good idea to resolve some of the hard questions in the past papers or in the book too. Lastly, do NOT worry before and during the exam since you've done more than enough to get a high grade .. :smile: