Edexcel S1 A Level Maths

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need help with part B and C

Hi, well the area of the bar is proportional to the frequency & for the one they've given, area = 60 (class width x height) so an area of 60 represents 90 people hence an area of 1.5 (90/60) represents 1 person & the area of those who took b/w 40 & 60secs is 20 x 5 = 100 so 100x1.5 =150 people. For part C just use the same method & add all the frequencies for those less than 80 together. :smile:

Reply 301

patterson

Original post by Fortitude

Thank you very much.

Reply 302

masryboy94

i don't like S1 not one bit !! lol as long as i get 48 UMS or above (E or above) i can still get that A* overall because of my grades last year. puts so much less pressure on me for friday !!

Reply 303

That_Clever_Guy

Original post by patterson

need help with part B and C

Hope that you can read it :smile:

ImageUploadedByStudent Room1368661734.622981.jpg

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Reply 304

That_Clever_Guy

Original post by masryboy94

i don't like S1 not one bit !! lol as long as i get 48 UMS or above (E or above) i can still get that A* overall because of my grades last year. puts so much less pressure on me for friday !!

lucky you man :smile:

i really love s1 its soo amazing cant wait to do S2

Reply 305

TheSnail

Does anybody have the Jan 13 paper and mark scheme?

Reply 306

nm786

Original post by g.k.galloway

Does anybody have the Jan 13 paper and mark scheme?

Paper: http://www.thestudentroom.co.uk/attachment.php?attachmentid=215489&d=1368468923
Mark Scheme: http://www.thestudentroom.co.uk/attachment.php?attachmentid=215491&d=1368468923

Reply 307

jadecross

Can someone tell me what P(B|R) means? I have no idea :frown:

Can't we just use words with probabilities?
I'm worried that they may use the letters above so it's best to learn it. Please help!

(edited 10 years ago)

Reply 308

usycool1

Original post by jadecross

Can someone tell me what P(B|R) means? I have no idea :frown:

Can't we just use words with probabilities?
I'm worried that they may use the letters above so it's best to learn it. Please help!

Probability that B happens given that R occurs. :smile:

Reply 309

TheSnail

Original post by nm786

Paper: http://www.thestudentroom.co.uk/attachment.php?attachmentid=215489&d=1368468923
Mark Scheme: http://www.thestudentroom.co.uk/attachment.php?attachmentid=215491&d=1368468923

Thank you!!

Reply 310

jadecross

Original post by usycool1

Probability that B happens given that R occurs. :smile:

oh thank you, you're a great helper! :smile:

Reply 311

Jam'

3 s.f.?

Probabilities usually take 4 d.p.

Reply 312

justinawe

Original post by jadecross

Can someone tell me what P(B|R) means? I have no idea :frown:

Can't we just use words with probabilities?
I'm worried that they may use the letters above so it's best to learn it. Please help!

It's easier to use shortened notation, who's got the time to write "the probability of B given R" every time? :tongue:

Reply 313

justinawe

Original post by Jam'

3 s.f.?

Probabilities usually take 4 d.p.

For normal distribution questions you mean? Yeah, take them to 4 d.p., because that's how they've given them in the tables.

Reply 314

Jam'

Original post by justinawe

For normal distribution questions you mean? Yeah, take them to 4 d.p., because that's how they've given them in the tables.

For probabilities in general.

Everything else to 3 s.f.

Reply 315

Fortitude

Original post by Jam'

For probabilities in general.

Everything else to 3 s.f.

I'd just write the whole no out & then round to 3sf but yeah as has been mentioned in normal distribution write what it says in the table.

Reply 316

usycool1

Original post by jadecross

oh thank you, you're a great helper! :smile:

You're welcome :hat2:

Reply 317

justinawe

Original post by Jam'

For probabilities in general.

Everything else to 3 s.f.

For other probability questions, you can almost always (possibly always) get exact values.

Markschemes accept answers to 3 s.f. anyway.

Reply 318

Fortitude

When drawing a regression line, do you only plot the means or do you have to plot anything else?

Reply 319

tigerz

Original post by Amydx6

How do you Unicode for standard deviation?

Posted from TSR Mobile

You have to uncode by multiplying/ dividing, as addition/subtraction has no effect on variance and standard deviation
So if coded standard dev is: (x-5)/10=20 Then the uncoded is simply: 20x10= 200. (you don't add 5)

In mean you have to uncode it all so if coded mean= x+25/5=10 then uncoded mean is (10x5)-25=25

In regression, coding has no effect on PMCC but if you're asked to find a certain value using the line you have to uncode by subbing in.

4. A farmer collected data on the annual rainfall, x cm, and the annual yield of peas, p tonnes per acre. The data for annual rainfall was coded using v= (x-5)/10
and the following statistics were found.

Svv = 5.753 . Spv = 1.688 . Spp = 1.168 . mean of p= 3.22 . mean of v= 4.42

(a) Find the equation of the regression line of p on v in the form p = a + bv. (4)

(b) Using your regression line estimate the annual yield of peas per acre when the annual rainfall is 85cm. In this case you sub in 85 to find V. You can then insert it into your original equation

markscheme for regression.png