Computing pre-release material AQA A

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Reply 580

ElMoro

Original post by Oliver17

Which one was question 10?

Keeping track of the number of moves

Reply 581

Mister Cery

I didnt have time to do the last 2 questions so thats about 20 marks gone not to mention quite a few more throughout the paper :frown:

. Probably got a C.

Reply 582

JoeUtd

Couldn't do the algorithm one on Python. Kept screwing up the loop. Wasn't sure what I was doing wrong. Gutted bout that, easily counts as a whole grade.

Think in general though I answered the questions well.

Reply 583

A Wise Ninja

Anyone get 400 for the sound maths question, thats what I got,

as it was 0.005 per sample, so 200 hertz

then doubled for Nyquists theorum?

Also, I finished the last one in the final second!!! realised what to do with 3 minutes of the exam left and pasted in the 3 printscreens all at 11:29 :eek:

I'm one lucky fudger.. haha.

Reply 584

mathieuh

Original post by A Wise Ninja

I'm one lucky fudger.. haha.

The answer was 600Hz, 6 oscillations in 0.02 seconds, which means 300 oscillations in 1 second, and double that according to Nyquist's theorem.

Reply 585

A Wise Ninja

****, I did a miss calculation.. ah well I suppose that'll only lose me one mark, not too bothered :smile:

Reply 586

JoeUtd

What about the vending machine one? That didn't make sense to me. One of the given examples was 10,50,50. How does that work?

Reply 587

Oliver17

Original post by mathieuh

The answer was 600Hz, 6 oscillations in 0.02 seconds, which means 300 oscillations in 1 second, and double that according to Nyquist's theorem.

Damnit!! I did the calculation and then forgot to double it... At least I explained the theory correctly, so that is method marks at least.

Reply 588

sl96

how comes ums never goes down

Reply 589

Mister Cery

**** I just realised how I was supposed to do the finite machine table.

Reply 590

h2shin

Original post by JoeUtd

What about the vending machine one? That didn't make sense to me. One of the given examples was 10,50,50. How does that work?

putting in 10, then 50 causes all of the coins to be returned, then putting in 50 gets the machine into the goal state.

Reply 591

ElMoro

I really hope I did enough for 107UMS. Annoys me that I know I would've done better if I just started revising earlier

Reply 592

mathieuh

Can anyone explain to me how the UMS system works?

Reply 593

iCiaran

Original post by mathieuh

Can anyone explain to me how the UMS system works?

Have a look for here for a brief idea to just get a feel for it without going in depth about how it is calculated...

Reply 594

fizzbizz

Original post by Oliver17

It asked what the size of the image would be in bytes. I believe the image was 8px by 8px with a colour depth of 2 bits.
So the calculation would have been:
(8 * 8) * 2 = 128 <- Size of image in bits, so to convert to bytes divide by 8
128 / 8 = 16 bytes
(I hope that is right :P)

My solution for that question (Java):

int calculateDistance(CellReference monsterPosition, CellReference playerPosition){

int distanceEast, distanceSouth;

distanceEast = monsterPosition.noOfCellsEast - playerPosition.noOfCellsEast;
distanceSouth = monsterPosition.noOfCellsSouth - playerPosition.noOfCellsSouth;

//If the values are negative, then multiply them by -1 to get the absolute value
// If we didn't do this, the value of distance would be negative if the player was above the monster
if(distanceEast < 0){
distanceEast = distanceEast * -1;
}
if(distanceSouth < 0){
distanceSouth = distanceSouth * -1;
}

int totalDistance = distanceSouth + distanceEast;

return totalDistance;
}

EDIT: I know I could have used Math.abs, but it said that extra marks were awarded for keeping it self-contained, so I preferred not to introduce outside classes and methods :P

aha yes I did this too, hi five!
although i just did distanceSouth = -distanceSouth;
seemed to do the trick too :biggrin:

Reply 595

xDanny 117

I did use Nyquests theorem for that question but went back on it as it asks you for the minimum frequency, and you sample at twice the minimum frequency.

I just wrote down 300 as that's the 'minimum frequency'

For gods sake! It's only 1 mark, but still :P

Reply 596

fizzbizz

Original post by JoeUtd

What about the vending machine one? That didn't make sense to me. One of the given examples was 10,50,50. How does that work?

It said if you insert more than 50p it'll return the coins
So 10 + 50 would be 60p which is too much, so it'll return the 50p and 10p coins, and then you just insert the 50p to get to the goal state :smile:

Reply 597

fizzbizz

Original post by D-Box

The paper definitely said how many more bits

how many more numbers you can make from changing the column variable to 16 you mean?

Reply 598

iCiaran

Original post by sl96

how comes ums never goes down

The marks are scaled to the UMS, so it is the same amount of UMS for each grade every year, but the number of raw marks to get that number of UMS changes...