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# OCR MEI C4 Mathematics June 2016 - Official Thread watch

1. a larger focal length led to a larger image
2. God. Question 5 & 6 threw me completely. Absolutely gutted.
Q5 I had no idea where to start and simply couldnt get anywhere. Q6 I must have done something wrong because I couldnt get my t's to cancel.
got dt/dx rather than dx/dt so got 4 instead of 1/4. Messed up on the ratio question despite getting correct lamda.
Absolute nightmare of a paper.
Only thing that's got me clinging onto an A* is that I think I got 72/72 C3 and 18/18 on the comprehension.
So bitter about the maths exams this year.
3. (Original post by HFancy1997)

1)Root10cos(theta+1.249)
Invalid because4/root10 is bigger than 1
2)P=2,Q=-2
3)Theta=90,26.565
4)volume=16Pie/3
6)Area was 8
7)Length 5root2
-Q(12/5,8/5,2)
Ratio 3:2
8)Constant of proportionality was 1/4
and k=0.811

Not sure about any others? They were mainly show thats werent they?

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I got the ratio as 2:3 from 2root2:3root2
4. (Original post by Danny.L)
Wouldnt it be 80 found it too small?
The larger the focal length, the smaller the field of view and thus images appear larger.
So for those above 80mm will prefer a larger image and will therefore think it looks too small, whilst those beneath 70 will be used to a larger field of view, so 75mm will look too large?
above 80 like a bigger focal length so like a smaller angle, but they have to do with a smaller focal length and a bigger angle so they'll find it bigger

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5. (Original post by groovy_q)
I got the ratio as 2:3 from 2root2:3root2
Yeah I cant remember which way but yeah its 2:3 I think I remwmber that too

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6. (Original post by Danny.L)
Wouldnt it be <70 found it too large?
and >80 found it too small?
The larger the focal length, the smaller the field of view and thus images appear larger.
So for those above 80mm will prefer a larger image and will therefore think it looks too small, whilst those beneath 70 will be used to a larger field of view, so 75mm will look too large?
With a smaller FOV, the image is larger. Therefore those who initially preferred 50 and 60mm, they prefer larger images. Using a 75 mm focal length will decrease the size of the image, therefore they think it is too small.
7. (Original post by decombatwombat)
With a smaller FOV, the image is larger. Therefore those who initially preferred 50 and 60mm, they prefer larger images. Using a 75 mm focal length will decrease the size of the image, therefore they think it is too small.
Completely agree

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8. also did you say as an assumption that the data is evenly distributed ?
9. A smaller length = greater vision. Therefore it is assumr that people below 70 likes a large view. So if they tried a 75 they will think its too small.

Vice versa.
10. wtf was 5)ii please enlighten me
11. (Original post by hbk1)
wtf was 5)ii please enlighten me
They were both show that qs werent they?

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12. (Original post by decombatwombat)
With a smaller FOV, the image is larger. Therefore those who initially preferred 50 and 60mm, they prefer larger images. Using a 75 mm focal length will decrease the size of the image, therefore they think it is too small.
If you read the extract, it said that the smaller the focal length, the larger the angle. Therefore the larger the field of view and smaller the image appears.
The larger the focal length, the more narrow the field of fioew and thus the larger the image appears.
So anyone about 80mm will think the image is too small and they prefer a higher focal length and thus smaller field of view so larger image.
Those who were less than 70mm prefer a smaller focal length, so a larger angle and therefore field of view, so will think it's too large.
13. How many marks was the volume of revolution one? I got it right up until where it was to be integrated which is where I went wrong. How many marks would I lose?
14. (Original post by MintyMilk)
Yeah, that must have been what we both meant. I went over the logic a good 10 times in the exam, so I'd be surprised if I got it wrong
So is it >80 too small and <70too large? Cuz except for that one I think I've got full marks
15. Anyone able to remind me of the questions? I want to get an unofficial mark scheme done for you guys
16. When you handle an actual camera with varying focal lengths, as you increase the focal length (50 -> 70), the image becomes a lot more zoomed in, and if you reduce it (50 -> 35) the image zooms out, and you get a wider field of view, and thus things appear smaller. In the survey, those who preferred the lower focal lengths will say that the image is too large because the image at 75mm will be much more zoomed in and therefore the wind turbine will become larger. Those who preferred the higher focal lengths will have found the field of view to have widened and the turbine to become smaller and thus will think that the image is too small.
17. (Original post by MintyMilk)
You mean an A*?
No A - I think the highest the A grade boundary has ever been is 75 and lowest 64 so maybe was a bit harsh, perhaps the A will be more like 67 as it was a hard paper although people seem to get better at acing the papers as the years go by...
18. (Original post by gregsonog)
When you handle an actual camera with varying focal lengths, as you increase the focal length (50 -> 70), the image becomes a lot more zoomed in, and if you reduce it (50 -> 35) the image zooms out, and you get a wider field of view, and thus things appear smaller. In the survey, those who preferred the lower focal lengths will say that the image is too large because the image at 75mm will be much more zoomed in and therefore the wind turbine will become larger. Those who preferred the higher focal lengths will have found the field of view to have widened and the turbine to become smaller and thus will think that the image is too small.
I did this but I was rushing and basically said large focal length=too small and vice versa. Reckon this would be enough for reasoning marks?

19. Here you go everyone !

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20. I personally felt that while the comprehension paper was quite easy as they come (again, just moi), and Part B of the core paper was very standard, Part A seemed a fair bit more difficult than in previous years.
For the independence part of the Part A parametric (Q6 I think), I did the tangent thing and even found the intercepts, so the answer was right there, but I then elected to find the area in terms of t after doing all the working and I don't know why... 5/7 OCR pls? Apollo where art thou. However, many of my friends didn't get that far. In fact, the Q8 parametric felt quite easy in comparison, though if you approached it by finding dx/dt instead of 1/(dt)/dx), you'd have a bad time.

Aside from Q6, I've also probably lost a couple of marks by fudging the last step of the last part of the stacked triangles question. T'was a mighty fudge. So idk. 85/90 would be nice.
From what I can tell the rest of it was fine. I've got the same answers as HFancy1997 if y'all need any more verification.

I'd be interested to know if anyone found Part A easier than part B.

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