Edexcel S1 - 15th June, 2016 [Exam Discussion]

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For question 2, I got Var(X) = 2.115.
For question 6, I got 4 hours 34 minutes (or 274 mins).

Absolutely not. You can never just randomly multiply anything by 100 - you could have multiplied by 100% (which is equal to one) - but the question did not specify to leave your answer as a percentage so any form (decimal, fraction, percentage, heck even a per mille) should be fine.

You got question 6 b wrong - for him to be in the top 20% his time would have to be below the mean value and hence this value would be the bottom 20% as it's faster (because the value of time is lower)

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Reply 1201

LuckyMN

Great, there's no way in hell I'm getting an A. Now I'm just praying for a B.

Reply 1202

Megan3245

Original post by Fmathslad

you are most likely an a2 resit, and you're not taking into consideration that the people who use student room are normal a/b grade students and you all forget about the countless numbers of people who will fail this and as there were no easy marks ( box plots) (draw venn diagram) in which people will pick all their marks up on. meaning boundaries will be significantly lower than last years by 2 marks give or take you found it easy because you're either retaking and have had 2 years of stats or you are naturally good at maths and will therefor be park of the a* boundary in which will not affect the other boundaries. so don't be so patronising for the other students by saying that the boundaries will be 64 for an A or definitely won't be sub 60 for an A.

I couldn't have said it any better! well said.

Reply 1203

Youraveragepleb

Original post by themechguy

I said the mean remains the same, but standard deviation is unchanged!

I didnt put any explanation dosn, do they need explanation for the marks? The question didnt say explain..

So in other words, both remain the same......

Reply 1204

Mariamjaan

Original post by Raaj11

Do u know what u got for you Sxy and the pmrc ?

How did u find, y and y2 because we need these to find syy. I want know if any got it

Reply 1205

khaleesi98

Original post by themechguy

I calculated Syy in a very complicated way by using the mean to find the sum of x, and the standard deviation to find the sum of x squared and then used the formula I know! Is this OK too for the 1 mark?

Never done a formula for Syy with mean and SD!

Yeah that's what I tried to do, spent so much time on it but didn't get to the answer 😅 does anyone know how we were meant to work it out for 1 mark?

Reply 1206

MathsFanatic!

Original post by iMacJack

Same here i think i got around the 206 area

Reply 1207

hbaig27

does anyone know how many marks the rebecca and sarah q was worth in total

Reply 1208

AmarPatel98

Original post by khaleesi98

Yeah that's what I tried to do, spent so much time on it but didn't get to the answer 😅 does anyone know how we were meant to work it out for 1 mark?

Sigma = root (Syy / n)

rearrange for Syy

Reply 1209

Megan3245

Original post by hbaig27

does anyone know how many marks the rebecca and sarah q was worth in total

4 i think

Reply 1210

JezDayy

anyone get the same as me for the Venn diagram

Reply 1211

MathsFanatic!

Original post by Mariamjaan

How did u find, y and y2 because we need these to find syy. I want know if any got it

Basicall you have to use the method from the previous question- if you know bar y ( mean of y) is = to 54 or whatever it was the that means: the sum of y / n is 54.

knowing the value of n is 8 hence work backwards meaning its 54x8.

and then do the same for when working out the sum of y^2 but using the variance equation.

Hope that helps :wink:

Reply 1212

pokepal4

What do you guys think will be the 100 UMS? Last year it was 73/75. Since this year's was tougher, you think it can go a lot lower?
Also note that in june 2015 IAL, 70/75 was 100 UMS (Suprising I know)

Reply 1213

AmarPatel98

Anyone get 33 people for the dinner?

Last question was 0.36 exactly btw

Reply 1214

MathsFanatic!

Original post by JezDayy

anyone get the same as me for the Venn diagram

Looool, thats what i was thinking in my head :p:

Reply 1215

themechguy

Original post by Youraveragepleb

So in other words, both remain the same......

Sorry I meant I said SD decreased lol

Reply 1216

hbaig27

Original post by Megan3245

4 i think

I mean the whole probability distribution question

Reply 1217

JAFF2400

anyone found unofficial mark scheme yet?

wiggles unoe

Original post by pokepal4

What do you guys think will be the 100 UMS? Last year it was 73/75. Since this year's was tougher, you think it can go a lot lower?

Go back to June 2010 and it was 69/75 for 100 UMS (in Jan 03, it was just 63! but the course is a bit different over a decade later).

So it can go a fair bit lower than 73/75 but you're assuming this year's paper was tougher. Personally, I would agree, but I wouldn't expect it to be below 71.