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# Edexcel s1 June 2016 unofficial mark scheme

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1. (Original post by bobbutitii)
cool story bro, you'll get used to it.
what brutality
2. (Original post by Kawaii289)
what brutality
love u b xx
3. (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
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
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
4. (Original post by bobbutitii)
love u b xx
lol
5. (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
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
Can someone tell how many marks I'll lose for the overall question if my P and Q were wrong, cause my working for the rest of q was all right, just used the wrong numbers
6. (Original post by Kawaii289)
lol
it wasnt a joke u, im serious xxxx
7. (Original post by hbaig27)
Can someone tell how many marks I'll lose for the overall question if my P and Q were wrong, cause my working for the rest of q was all right, just used the wrong numbers
some of them, all of them and a few of them
8. (Original post by bobbutitii)
it wasnt a joke u, im serious xxxx
wow haha
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
Lol you're salty
10. Is the height exactly 17? Cos I got a decimal lol

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12. (Original post by zhzstudent)
please can you tell me how you worked out Q2 f i and ii ? like the general ideas of going about it ? thank you
This should explain it, particularly the top row and top right section:
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
I'll add it, but I could see Edexcel going either way.
14. That exam was so hard wtf
15. For the number of diners, did anyone get 16 or 17?
16. (Original post by logicmaryam)
Hey guys
Was told to post my answers on a separate thread so it doesn't get lost in the other thread.

Predicting 58 ish is an A and not much lower because it wasn't that bad of a paper. Loads of people thought it was OK or slightly harder. Theory questions threw me off a bit though.

Q1. 11 total i think
a) was Sdd or something (3)
b) wiggles is the response variable as it changes depending distance (1)
c) r = 0.722 + 0.014d
d) d= 350 sub in so w = 5.6 ish?
Q2 Sarah one
a) equation is 2p + q = 0.5
b) a= 0.175 b= 0.15
c) idk
d) E(R) = 0.45?
e) Sarah wins = 0.475 Rebeccawins= 0.375

Q3 with frequencies?
a) heigh of bar and width igot something like 34cm and 1cm?
b) show that Syy is … (1) didn’tdo this right lol
c) PMCC
d) SD
e) What were the other questions?

Q4 Hotel one
a) 0
b) t =0.03
c) u = 0.22
d) 0.45 and 15/37
e) diners 16? Some people say 33

Q5
a) median 3.47
b) SD = 0.689?
c) mean proof 3.43
d) Probability baby wasunder 3kg something like 0.2546
e) explain the use ofthe model? (2)I said that althoughthe range chosen was appropriate as mean was 3.43 for both and SD was close tothe calculated one, there is negative skew as median>mean so not good to use this model as mean and SD are affected by skew.
f) effect of adding baby weight of 3.43 on (3)
i) mean – I said staysthe same because I sneakily calculated it , because the frequency becomes 51and value is within range or something
ii) SD change "Others said it stayed thesame, but I wrote that it decreases, because now the average distance from themean is slightly less (as n has increased by 1 but deviance hasn't changed)".

Q6.
a) 0.0668 men took over 300 min to run
b) needs to run below 206.33 minutes to be in 20% of people who finish first
c)
d) the mew one0.18/0.5 = 0.36 (3)

Let me know what I'm missing and I've done wrong as well as the marks for each if you remember
I have the mean decreasing as it would be calculated using 3.25 as the midpoint of the class which is obviously less than 3.43. I really struggled with that SD part after it though, but I put something similar to yourself I think.
17. (Original post by C-Dog)
I have the mean decreasing as it would be calculated using 3.25 as the midpoint of the class which is obviously less than 3.43. I really struggled with that SD part after it though, but I put something similar to yourself I think.
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.
18. 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.
19. (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
How much was the histogram question on height and width worth? and the same with 4)dii and e.
20. (Original post by brandonmcb8)
How much was the histogram question on height and width worth? and the same with 4)dii and e.
Sorry, I didn't have the time to get exact marks. I would imagine 2-3 for each, but I'm not sure.

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