STEP 2016 Solutions

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Reply 20

Zacken

Original post by student0042

I left my answer was ((7^7 + 1)^3 - sum of 7's)((7^7 + 1)^3 + sum of 7's). :redface:

Reply 21

student0042

Original post by Zacken

I left my answer was ((7^7 + 1)^3 - sum of 7's)((7^7 + 1)^3 + sum of 7's). :redface:

That probably would have been better. Oops.

Reply 22

Zacken

Original post by student0042

That probably would have been better. Oops.

I don't think it would have... I'll probably get docked a mark or two. Ahhhh.

Reply 23

student0042

Original post by Zacken

I don't think it would have... I'll probably get docked a mark or two. Ahhhh.

Really? Did it want the answer like this? I don't remember what form it said, I thought it was just some form with 7^7 in it.

Reply 24

Zacken

Original post by student0042

Really? Did it want the answer like this? I don't remember what form it said, I thought it was just some form with [math] 7^7 [/math] in it.

It said "factors written as a sum of various powers of 7", I'm not sure if (7^7 + 1)^3 counts. :frown:

Reply 25

student0042

Original post by Zacken

It said "factors written as a sum of various powers of 7", I'm not sure if (7^7 + 1)^3 counts. :frown:

I'm not sure either, but (7^7 + 1)^3 looks a lot nicer.

Reply 26

rohanpritchard

Original post by Zacken

Just attaching it in big size for you:

(side note, this was a gift question!)

(other side note, I forgot sin -4 was positive...)

How many marks do you recon lost for not including where it was discontinued? I put the y values but I didn't get what it meant.. Which was kind of stupidly obvious now... That's in all parts I didn't do it

(edited 7 years ago)

Reply 27

Zacken

Original post by rohanpritchard

How many marks do you recon lost for not including where it was discontinued? I put the y values but I did get what it meant.. Which was kind of stupidly obvious now... That's in all parts I didn't do it

Probably 4/5 marks?

Reply 28

kelvin1338

Hey Zacken, what do you think is roughly going to be a grade 2 based on this year's paper difficulty? Thanks

Reply 29

Zacken

Original post by kelvin1338

Hey Zacken, what do you think is roughly going to be a grade 2 based on this year's paper difficulty? Thanks

My honest opinion is that it'll be about 62 for a 2.

Reply 30

Duskstar

I did not do as well on this as I wanted aha. I need a 2 for my insurance which I think I should have managed, but I wanted a 1. Then again it's probably my fault for not doing enough practice for it...

On question 2 I goofed on part ii and couldn't work out what to substitute oops, and on question 3 I didn't include the dots for the discontinuity...

Reply 31

rohanpritchard

STEP 1 Q9 solution. I couldn't remember for SURE which way round they put the coefficients of friction but I'm pretty sure it's this way, doesn't actually make any difference for the answer anyway. I realised I got the last bit wrong in the actual exam because I didn't account for the force due to friction at the rail also changing direction (I only changed it at the wall) -_-. This is correct here though.

(edited 7 years ago)

STEP1 2016 Q9.pdf716.9KB

Reply 32

Zacken

Original post by Mathemagicien

Yay! That's the answer I got. :biggrin:

Btw, e simplifies to sqrt 5 - 2

Yep, couldn't be bothered in the exam though. As it is, I spent 15 minutes checking everything because I was convinced my answer wasn't correct, with all the sqrt(5) shiz.

Reply 33

jjsnyder

Original post by Zacken

Yep, couldn't be bothered in the exam though. As it is, I spent 15 minutes checking everything because I was convinced my answer wasn't correct, with all the sqrt(5) shiz.

I did exactly the same, thought it would be a nice fraction so spent ages checking.

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Reply 34

Marxist

Original post by Ecasx

STEP I 2015 Q12

(i) Alice tosses a fair coin two times and Bob tosses a fair coin three times. Find the probability that Bob obtains more heads than Alice.

(ii) Alice tosses a fair coin three times and Bob tosses a fair coin four times. Find the probability that Bob obtains more heads than Alice.

(iii) Alice and Bob both throw a fair coin n times. The probability that they obtain an equal number of heads is p1, and the probability that Bob obtains more heads is p2. If Bob now throws the coin n+1 times, find the probability (in terms of p1 and p2) that Bob throws more heads than Alice. Hence generalise your results to parts (i) and (ii).

Spoiler

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Oh damn that's quite an easy question. :smile:

Reply 35

KingRS

Spoiler

(edited 7 years ago)

Reply 36

jahovasfitness

Original post by Zacken

I left my answer was ((7^7 + 1)^3 - sum of 7's)((7^7 + 1)^3 + sum of 7's). :redface:

what do you think the mark weighting will be for parts 1 and 2

Reply 37

jahovasfitness

Original post by smartalan73

STEP I, Question 3

graphs 001.jpg

I stupidly marked the coordinates of the points at the beginning and ends of the horizontal lines. Given that I still got all of the shapes right, how many marks would I have lost do you think?

Reply 38

smartalan73

Original post by jahovasfitness

I stupidly marked the coordinates of the points at the beginning and ends of the horizontal lines. Given that I still got all of the shapes right, how many marks would I have lost do you think?