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# Edexcel s1 June 2016 unofficial mark scheme

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1. 1.0.994
w=0.721 + 0.0142d
5.691 response was wiggle
2.p=0.175 q=0.15
varx=2.115
E (r) was 0.45 rebecca and sarah winning 0.475 0.375
3. 2.35 -133.9 -0.754
4.0 0.03 0.22 0.45 0.405 33 was number of diners
5. K=0.5
h=17
med=3.47
0.68
0.2546
6. 0.0668
206.336
0.36

Feel free to correct or give answers to non numerical questions
2. could you format it a bit better please
3. 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
4. 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
5. (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 63+ is an A and not lower because it wasn't that bad of a paper. 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) idkd) E(R) = 1/E(X) so 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 – the SDincreases? Don’t remember. Because there are more values to be accounted for inthe calculation so spread is increased?

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
Height for the bar is 17cm and the width is 0.5cm.
6. nice, add some spoilers to each questions.

also, itd be a cool idea if you found out the marks of each question and put a strawpoll asking how many marks you got, that way we could guess grade boundaries a lot easier.
7. (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 63+ is an A and not lower because it wasn't that bad of a paper. 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) idkd) E(R) = 1/E(X) so 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 – the SDincreases? Don’t remember. Because there are more values to be accounted for inthe calculation so spread is increased?

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
dont agree with 3a
i think it should be w=0.5 from comparing class width
area of given bar =4
A=kF
4=k8 k=0.5
so area of this bar =0.5x17=8.5
h=8.5/0.5=17
8. (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
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
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
a. 2.35
b. Show that
c. -133.9
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
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
a. Width 0.5, Height 17
b. 3.47 (median)
c. i. Show that
ii. Standard deviation = 0.680
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
a. 0.0668
b. 206 - The lowest 20% of times were the fastest 20% of runners.
c. 0.36
Just out of interest how did you reach the answer for 2(e). What did you have to do to the given Probability Distribution table?
9. (Original post by logicmaryam)
ii) SD – the SDincreases? Don’t remember. Because there are more values to be accounted for inthe calculation so spread is increased?
But the new value was exactly the same as the mean, so the SD (average distance from mean) can't increase. Others said it stayed the same, but I wrote that it decreases, because now the average distance from the mean is slightly less (as n has increased by 1 but deviance hasn't changed).
10. (Original post by KloppOClock)
nice, add some spoilers to each questions.

also, itd be a cool idea if you found out the marks of each question and put a strawpoll asking how many marks you got, that way we could guess grade boundaries a lot easier.
Sorry, why do I need to spoiler answers? If someone's on this thread they'll want to see answers right? I'm new to this so sorry if there's another reason

(Original post by SANTR)
Just out of interest how did you reach the answer for 2(e). What did you have to do to the given Probability Distribution table?
I found the reciprocal of each score, then multiplied by the probability. Have to say I wasn't sure on that one.
11. (Original post by veldt127)
Sorry, why do I need to spoiler answers? If someone's on this thread they'll want to see answers right? I'm new to this so sorry if there's another reason

I found the reciprocal of each score, then multiplied by the probability. Have to say I wasn't sure on that one.
So you divided each of the observations by 1 and then multiplied the 'same' probabilities with each corresponding 'new' observation i.e. 1/ each observation?
12. 1d is 5.7 to 2 sig figs
13. (Original post by veldt127)
Sorry, why do I need to spoiler answers? If someone's on this thread they'll want to see answers right? I'm new to this so sorry if there's another reason

I found the reciprocal of each score, then multiplied by the probability. Have to say I wasn't sure on that one.
so it doesnt take up half the screen, its just nicer formattin
14. (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
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
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
a. 2.35
b. Show that
c. -133.9
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
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
a. Width 0.5, Height 17
b. 3.47 (median)
c. i. Show that
ii. Standard deviation = 0.680
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
a. 0.0668
b. 206 - The lowest 20% of times were the fastest 20% of runners.
c. 0.36
I got these wrong:
2 f ii)
3 e) maybe I got one mark
4 d i)
4 e)
5 e) lost 1-2 marks
5 f ii)
6 c) maybe I got one mark for getting 0.5 as one of the probabilities.

Oh wells

Posted from TSR Mobile
15. Hey everyone, I got 0.6 for 4.a (the hotel one), is it right?? I looked at the answers above it said 0 but I just guessed anyways
16. 3c> was -131.9 and 5 Cii> was 0.689
17. (Original post by SANTR)
So you divided each of the observations by 1 and then multiplied the 'same' probabilities with each corresponding 'new' observation i.e. 1/ each observation?
Yeah, I think you've worded that right. It was a weird question

(Original post by KloppOClock)
so it doesnt take up half the screen, its just nicer formattin
Ah I see, I'll get on that
18. 5f)i Didn't the mean decrease? It fell into the 3-3.5 one which had a midpoint of 3.25 which is less than the mean
19. Q1: 2,1,2,4,2
Q2: 1,3,2,2,3,4
Q3: 3,1,2,2,2
Q4: 1,4,2,4,2
Q5: 3,2,3,3,3,3
Q6: 3,3,3

those were the marks for each part of the question.
20. (Original post by Jackhawkins21)
3c> was -131.9 and 5 Cii> was 0.689
Was that using exact values? If enough people agree on this I'll change it.

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