[Mr M]

Mr K's OCR (not OCR MEI) S1 answers May 2012


1. (i) r = -0.709 (4 marks)

(ii) y = -0.0185x + 8.5742

Estimate £3394 (4 marks)

(iii) Correlation does not imply causation (1 mark)


2. Mean = 1.53 kg

Standard deviation = 14.7 g (6 marks)


3. (i) 22.5 (1 mark)

(ii) w = 0 and x = 0 (2 marks)

(iii) 40 or 40.75 (2 marks)

(iv) Gives a visual display of distribution OR original data preserved (1 mark)

(v) Shows spread/IQR/median more clearly (1 mark)


4. (i) Top pair of branches Red 4/5 and Black 1/5

Bottom pair of branches Red 1 and Black 0 (2 marks)

(ii) 1/3 (3 marks)

(iii) 4/5 (2 marks)


5. (i) (a) 1 (1 mark)

(b) -1 (1 mark)

(ii) 0 (3 marks)

(iii) Completely agreed, Completely disagreed, No agreement (3 marks)


6. Profit = £110 (5 marks)


7. (i) (a) 2520 (2 marks)

(b) 720 (3 marks)

(ii) (a) 21 (1 mark)

(b) 10/11 (3 marks)


8. (i) 0.825 (2 marks)

(ii) (a) 0.265 (2 marks)

(b) 0.168 (6 marks)


9. (i) (a) 0.0590 (3 marks)

(b) 0.410 (3 marks)

(ii) (a) 0.0951 (2 marks)

(b) 0.513 (3 marks)


These answers were produced by my colleague Mr K and not by me so there is probably little point asking me about them. Hope you find them useful though!

[ILovePi]

Thanks Mr M!
Any idea what raw mark might get UMS 100? (From the looks of things, I got roughly 67/72)

[ILovePi]

Also, can you ask Mr K to verify 3 (i) and (iii) please if possible, especially 3 (iii) as it was asking for values of two things from a stem and leaf diagram, but they were in the 3|x section, not 4|x

[strikerextreme]

thanks for these
i lost loads of marks <40/72

[Jack976]

(Original post by ILovePi)
Also, can you ask Mr K to verify 3 (i) and (iii) please if possible, especially 3 (iii) as it was asking for values of two things from a stem and leaf diagram, but they were in the 3|x section, not 4|x

They were in between the last value of the 3 section and the first of the 4 section - it just happened that they were both actually 40/40+

[ILovePi]

(Original post by Jack976)
They were in between the last value of the 3 section and the first of the 4 section - it just happened that they were both actually 40/40+

But as they were in the 3 section, surely they are 38 or 39?

[ht4]

for 3ii do you think youd get the marks if u put x=30 w=30 instead of 0?

[Jack976]

(Original post by ILovePi)
But as they were in the 3 section, surely they are 38 or 39?

As far as I remember, the last three values in the 3 section were 38, 3W and 3X (or two other letters)
This meant X and W were either 38 or 39 - and the UQ was 1/4 of the way between The last value and 46, so therefore if 38 was the last value, (46-38)x0.25 + 38 is 40, and the same for 39 game an UQ of 40.25 As far as I know

[As_Dust_Dances_]

Anyone know if you put 0.01 for the standard deviation would that still be correct? I also put 1.53 for mean but I didn't put it in (kg)..

[Lucozad]

Hello, Mr K.

[max25]

estimations for the raw mark 90ums?

[Jack976]

(Original post by As_Dust_Dances_)
Anyone know if you put 0.01 for the standard deviation would that still be correct? I also put 1.53 for mean but I didn't put it in (kg)..

Did you write down the answer to 3 s.f at some point in your working? Your'e only meant to be penalised once for using too many/little s.f. so it should only knock off 1 mark, as long as they could see you arrived at the correct answer somewhere (from looking at past mark schemes)

[Notsocleverstudent]

isn't 4 iii 3/5? not 4/5?

[As_Dust_Dances_]

(Original post by Jack976)
Did you write down the answer to 3 s.f at some point in your working? Your'e only meant to be penalised once for using too many/little s.f. so it should only knock off 1 mark, as long as they could see you arrived at the correct answer somewhere (from looking at past mark schemes)

Yeah, I think I remember writing down something like 0.0147 but then left my final answer as 0.01

[BIG Y]

urghh looks like i lost about 10+ grrrrrrrrrrrrr and i failed my D1 hate applied mathsssssss

[Mr M]

(Original post by ILovePi)
Also, can you ask Mr K to verify 3 (i) and (iii) please if possible, especially 3 (iii) as it was asking for values of two things from a stem and leaf diagram, but they were in the 3|x section, not 4|x

I just checked it myself.

The possible values of z were (3)8 or (3)9 but there is a big gap to the next number 46. This puts the upper quartile into the 40s.

[ht4]

i think it will be 52/72 for an A what does everybody else think?

[Mr M]

(Original post by ht4)
for 3ii do you think youd get the marks if u put x=30 w=30 instead of 0?

Possibly. You will definitely get at least 1 mark.

[Doctor.]

(Original post by Mr M)
I just checked it myself.

The possible values of z were (3)8 or (3)9 but there is a big gap to the next number 46. This puts the upper quartile into the 40s.

I found out the values for z were 38 or 39

How many marks would I get for that?

PS thank you and we love you!

[Mr M]

(Original post by As_Dust_Dances_)
Anyone know if you put 0.01 for the standard deviation would that still be correct? I also put 1.53 for mean but I didn't put it in (kg)..

If you put 0.0147 kg that would be fine. Rounding to 0.01 is likely to lose 1 accuracy mark. The front of the paper tells you to use 3 s.f. for non-exact answers.