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Edexcel s1 June 2016 unofficial mark scheme

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1. (Original post by googleit)
Mean slightly decreases. It adds one to the frequency of the 3-3.5 class and if you actually did the calculation, its shown to decrease. This is because the effect of 3.43 goes onto the midpoint of the class, 3.25 which is less than the mean. Amend
wrong.
you combine the means. u dont add it to the frequency table
2. (Original post by CaiusMartius)
To my understanding, since you actually have a value (3.43), you didn't need to worry about the classes and midpoints. It would be very stupid/sneaky of Edexcel to give you a value which is exactly equal to the mean and then not intend you to use it in the way which you would expect.
It was 2 marks which would suggest some kind of reasoning is needed other than 'oh look it's the same number' and as for using the combining means formula, it said not to do any calculations.
3. Has anyone done an unofficial mark scheme like there was for m1? - http://www.thestudentroom.co.uk/show....php?t=4150149
4. what was the question for 4a
5. bad one was that
6. (Original post by C-Dog)
It was 2 marks which would suggest some kind of reasoning is needed other than 'oh look it's the same number' and as for using the combining means formula, it said not to do any calculations.
Firsyly, it was 3 marks.

1 mark for saying mean stays the same.
1 mark for saying SD decreases.
1 mark for reasoning for this.

Also, who said you were calculating anything?
7. (Original post by CaiusMartius)
Firsyly, it was 3 marks.

1 mark for saying mean stays the same.
1 mark for saying SD decreases.
1 mark for reasoning for this.

Also, who said you were calculating anything?
i thought SD would stay the same as there is no deviation from the mean. The baby was the same weight as the mean. I thought the Mean would decrease because it is getting closer to the normal mean.I dunno
8. For all those saying the mean decreased because it was 3.25, tell me, how did you then go on to determine the standard deviation change without any form of calculation ???
9. (Original post by veldt127)
On the topic of the mean-
If you put the new value, 3.43, into the table and work out a new mean, the longer way, the mean would decrease. However a better way would be to combine means, which would keep it the same.

I would imagine Edexcel would allow either as you can reason it either way, but this way makes more sense.
I think they'll allow either but staying the same makes more sense to me. Can we stop arguing this, because both might be allowed?
10. What do u think the raw mark boundary will be for an A?
11. How did you answer how the PMCC would change I said that 14mm was greater than the mean number of rain as well as 70 hours so this shows positive correlation which would make the PMCC weaker
12. (Original post by veldt127)
I think they'll allow either but staying the same makes more sense to me. Can we stop arguing this, because both might be allowed?
It said with no further calculations
13. For the p and q values I got different values to what everyone is saying 😭😭 will I still get SOME carry through marks ??
14. (Original post by igotohaggerston)
It said with no further calculations
I wasn't suggesting doing a calculation, I was suggesting how you would add the new value. Both ways require a calculation, but the statement you make doesn't
15. (Original post by veldt127)
Ok, I managed to get all my answers stored in my calculator at the end, this is what I got. Not 100% sure on all of them, but we can compare.

Question 1
Spoiler:
Show
a. Show that
b. W - can't remember reasoning
c. 0.994
d. 0.0772 + 0.0142d
e. i. 5.69
ii. Reliable as the data was interpolated; it was within the range
Question 2
Spoiler:
Show
a. 2p + q = 0.5
b. q = 0.15
c. p = 0.175
d. 2.12
e. 0.45
f. i. 0.475
ii. 0.375
Question 3
Spoiler:
Show
a. 2.35
b. Show that
c. -133.9 - possibly -131.9
d. -0.754
e. Increase - I tried using the variables from the new week and recalculating r, and it was higher than the original. I said because the values were both higher than the means; I'm not sure at all on this one.
Question 4
Spoiler:
Show
a. 0
b. t = 0.03
c. u = 0.22
d. i. 0.45
ii. 15/37
e. 33 people have dinner (40*0.18) + (37*(15/37))
Question 5
Spoiler:
Show
a. Width 0.5, Height 17
b. 3.47 (median)
c. i. Show that
ii. Standard deviation = 0.680 - possibly 0.689
d. P(W<3) = 0.2546
e. No - the mean is not equal to the median suggesting asymmetrical skew18% of babies were less than 3kg, but her model predicted 25.46%
f. i. Mean remains the same as the new value is the mean
note: mean might decrease as it adds a value to the 3-3.5 group.
ii. The standard deviation decreases as the variance decreases with a new value close to the mean
Question 6
Spoiler:
Show
a. 0.0668
b. 206 - The lowest 20% of times were the fastest 20% of runners.
c. 0.36
For the question about the weights of babies the midpoints and frequencies of the table were
x f
1 1
2.5 8
3.25 17
3.75 17
4.5 7
(I think) (don't know how to put it in a table, 1st number is midpoint 2nd number is frequency)
16. Check out the Hitler reacts. had me dying
17. (Original post by veldt127)
Sorry, I didn't have the time to get exact marks. I would imagine 2-3 for each, but I'm not sure.
Thanks
18. I reckon 55 for an A
19. (Original post by Zakariya121)
I reckon 55 for an A
Sorry to burst your bubble but i think it might be higher :/
20. (Original post by Zakariya121)
I reckon 55 for an A
Not a chance.

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