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Mr M's OCR (not OCR MEI) Core 1 Answers May 2013 Watch

1. (Original post by Mr M)
Q4) that's fine

Q5) lose 1 mark

I've provided a link to the correct graph on wolfram alpha a few pages ago.

Thank you! And for the last question if I had the correct method throughout but made arithmetic errors which were crazily stupid in getting me k=49 I should lose about 4? I expanded the brackets, then dy/dx=0 at x=-3 so subbed that and worked out k

for the second part I got the answer of minimum because d2y/dx2 was greater than 0 it was 12 I think would I still get the marks despite wrong value for x?

Finally for the last part, if I made gradient of curve=gradient of tangent so my dy/dx value equal to 9 and tried to factories how many marks would I lose? It was impossible with the values I had though

sorry about the number of questions but really appreciate all the help

thank you
2. (Original post by Mr M)
Get one or two marks for finding P.
Is that the same if I calculated the midpoint of PQ by mistake?

Posted from TSR Mobile
3. Hi Mr M
For question 9 where we had to find K i got k to be -6 instead. How many marks do you think i would get...if i just added up wrong at the end.

Also i did have root 81/4 but at the last minute i took off the root sign and put it to just 81/4 how many marks would i lose??

For the completing the square question then finding the coordinates of minimum point if i completed the square wrongly....then would i get no marks for the miminum point part if i used what i got in the complete the square part???

Thank you
4. For question 5)ii). I put y=2/(x^2)+5. Will I get 1 mark for this because of M1? Also for the radius of the circle, I put root40 instead of 2root10; will I still get the marks?
5. (Original post by gingerberry)
Hello, for the last part of the last question, I did all of the correct working up until the last part where I got to the quadratic equation and factorised it but didn't put what x or y equaled (so no coordinate so I will lose the answer mark but will I get credit for the working up to that point?) but then I doubted myself and tried a different method afterwards which didn't come to an answer (as the method I did first was right) and I didn't cross out my first correct method but will I get penalised for then including a wrong method afterwards even though the second method didn't come to an answer either? Or will they just ignore my second wrong method and give me a few method marks for t hr first correct method or will I get 0 marks for that question?? Really worried as I need an A because this is a resit. Also, for the question where you had to find the length, I put "the square root of 81/4" but then afterwards instead of simplifying that down to just 9/2 I put "9/2 or -9/2" will I still get marks for that question or will the penalise me for including a wrong answer with my right answer and mark the whole question wrong??!*
The second attempt will be marked.

Drop one mark for -9/2.
6. (Original post by Z.M.1)
Thank you! And for the last question if I had the correct method throughout but made arithmetic errors which were crazily stupid in getting me k=49 I should lose about 4? I expanded the brackets, then dy/dx=0 at x=-3 so subbed that and worked out k

for the second part I got the answer of minimum because d2y/dx2 was greater than 0 it was 12 I think would I still get the marks despite wrong value for x?

Finally for the last part, if I made gradient of curve=gradient of tangent so my dy/dx value equal to 9 and tried to factories how many marks would I lose? It was impossible with the values I had though

sorry about the number of questions but really appreciate all the help

thank you
You might only lose 3 marks in total across question 10.
7. (Original post by ZachM)
Is that the same if I calculated the midpoint of PQ by mistake?

Posted from TSR Mobile
I'm not really sure as that is such an odd thing to do.
8. (Original post by 4Hyunah)
Hi Mr M
For question 9 where we had to find K i got k to be -6 instead. How many marks do you think i would get...if i just added up wrong at the end.

Also i did have root 81/4 but at the last minute i took off the root sign and put it to just 81/4 how many marks would i lose??

For the completing the square question then finding the coordinates of minimum point if i completed the square wrongly....then would i get no marks for the miminum point part if i used what i got in the complete the square part???

Thank you
drop 1

drop 1

You will probably be able to get full marks on the minimum bit from using your wrong completed square bit.
9. (Original post by eddieko555)
For question 5)ii). I put y=2/(x^2)+5. Will I get 1 mark for this because of M1? Also for the radius of the circle, I put root40 instead of 2root10; will I still get the marks?
root 40 is fine - the other bit will probably get no credit.
10. HI,
Please may I know what question 9 was
thanks
11. Mr M? I did all the revision I can, i understood all the questions. How would you avoid silly mistakes? And how can I prepare for questions like the last question of Core1 yesterday? A question with an answer I have never seen before, with two values of x and got it wrong in the end. Where can I go to do really-difficult questions like those. If you were a student, How would you prepare for Core2 this Friday?
12. (Original post by ashraf549)
Mr M? I did all the revision I can, i understood all the questions. How would you avoid silly mistakes? And how can I prepare for questions like the last question of Core1 yesterday? A question with an answer I have never seen before, with two values of x and got it wrong in the end. Where can I go to do really-difficult questions like those. If you were a student, How would you prepare for Core2 this Friday?
Past papers all day long. The last question yesterday was similar to the last question in jan 2013..
13. (Original post by Mr M)
Mr M's OCR (not OCR MEI) Core 1 Answers May 2013

1. (i) (2 marks)

(ii) (1 mark)

(iii) (1 mark)

2. or (5 marks)

3. (i) (3 marks)

(ii) (2 marks)

4. (i) (3 marks)

(ii) (3 marks)

(iii) (2 marks)

5. (i) Correct sketch (2 marks)

(ii) (2 marks)

(iii) Stretch scale factor parallel to y axis (2 marks)

6. (i) Centre and radius (3 marks)

(ii) (2 marks)

7. (i) (2 marks)

(ii) (5 marks)

8. (7 marks)

9. (i) Correct sketch with intersections at (-1.5, 0) and (2, 0) and (0, -6) (5 marks)

(ii) OR (either will be marked correct) (3 marks)

(iii) (4 marks)

10. (i) (7 marks)

(ii) Minimum (2 marks)

(iii) (5 marks)

I'll be around to answer questions shortly.
For question 2, I did all the right working out but my final answers were x=1/2 and x=-1/2 because I remembered, if you root anything, it should be plus or minus, and I stupidly didnt relize you could cube root a negative so I explicitly wrote, cant cube root -1!!! How much marks would I get for that question?
Also for 5ii, I said a parallel stretch in the x axis by 0.5, would I still get a mark?
For 6i, I wrote the radius as , would I still get a mark? I got the right center.
14. if i wrote squash by 2 parallel to y, instead of stretch by 1/2....?
15. I know nobody knows the grade boundaries but would 71/72 get 100 UMS?
16. Can someone help me ? I Have the CASIO fx-991ES PLUS calculator and just wanted to check whether it was allowed in OCR Core 2 exams?
Thanks
17. Mr M,
For the completing the square question, I think in my working put I wrote down the question wrong as "3xsquared +9x - 10" instead of "3xsquared + 9x +10" so my working out for that question goes as follows:
3xsquared +9x - 10
3(xsquared +3x) - 10
3(x + 3/2) -10 -(3 times 1.5squared)
Will I still get 2 marks out of 3 as I got the "3" and the "3/2" right, or will I get 0 marks for that question as every stage of working contains "-10" as I wrote it down wrong and therefore every working stage included this one wrong thing??
And on the next question, that mean my y Co-Ordinate was wrong as I used the answer from the previous question, but I got the x Co-ordinate right, so how many marks out of 3 would I get for that question (1,2 or 0)????????
Thankyou
18. what was the question for 5 ii please
19. Just 2 quick questions
For 5(iii) I described the transformation of y = 1/x^2 to 2 / x^2 rather than the other way round. Will I lose 1 or 2 marks? I did put stretch parallel to the y-axis.

And for 8 I left the equation of the line in y = mx + c form. How many marks will I lose for that?
20. For 5 (iii) would i drop a mark for not putting parallel, i put stretch scale factor of 1/2 in the y axis?

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