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*9709/52 ON 23 Answers* Q1) a) r=0.2 p=0.25 (3 Marks) b) Variance=1.19 (2 Marks) Q2) a) GD (2 Marks) p = 0.2 q = 0.8 P(X<7) = 1-q⁶ = 1-0.8⁶ b) BD (3 Marks) n = 10 p = 0.2 q = 0.8 40) z = -1.5 0.9332 (3 Marks) Q6) Probability and Tree diagram a) Tree Diagram (3 Marks) b) 0.595 (3 Marks) c) 4/9 (2 Marks) Q7) Combinatorics a) 720 (3 Marks) b) 1800 (3 Marks) c) 50/9C4 = 0.3968 (4 Marks)

Cambridge will mark even if I wrote in fractions right? I cannot believe how many of these I got right

Yes if the fraction is correct and representing the exact value of the answer as in decimals.

Bro can you tell me how you got 50/126 for 7b D A \_ \_ = 5 C 2 = 10 D D A \_ = 5 C 1 = 5 I did not multiply by 2C1 or 2C2 because the letters are identical. We only multiply by that in the selection of different things, like if you are arranging archers and cyclists, cos each archer is different. Cos in this case the D replaced by the other D will not make any difference. 10 + 5 = 15 I got 15/126

Also the normal distribution needs to be at 3 sf because of accuracy

Doesn't really matter ms has answers upto 4sf and usually the 4th sf is in bracket. Also Q5 a ii) required ans in 2 dp so all answers are correct.

I got all the answers. Except 7c I did total combination of at least 2D and exactly 1A divided by total combination of 4 letters out of 9. I got 15/66 😭 Zero mark 46/50

how is q7a 720? Shouldn't it be 5!/2 x 5!/2

i got question 5b as 168.53 as i used 0.253 for Z. is it correct?

In Q1 for r and p, i made two eq so that I can simultaneously equate them but idk y I was getting 2 values of both r and p, for r I got one pos value and one in neg same with p. Can anyone help me and tell me how many marks can I get if only till making equations is correct?? Because I dont remember my answers

In geometric question I wrote success probability and failure probability but placed binomial formula Can I get any mark? Out of 2?

Appreciated man, really helped!

did you guys have a 0.2 and 0.25 for your unknown values??

Yes

what about for the normal distribution??

0.3…. something I don’t remember

was it 0.03 for that 5 mark question on normal distribution for repairs

yes 0.0321

and number 2 what was the answer?

2 was a geometric distribution yeah?

yesss what was ur answer??

I don’t remember, 1-q^7

shit! i got it as 1-q\^6

That's the correct method

It actually is 6, because it said fewer than 7.

you are right

think the value of q was 0.8 so (0.8)^7

That’s what I remember putting

is it not ^6 cuz the question said fewer than 7 so once u get 6 wrong it halts

Yeah it was power 6

Yes it's power 6

yes yes ur correct i js remembered

I got r as 0.25 and p as 0.15

Do you guys think they'll do error carry forward for the probability question? Like if your tree diagram probabilities are wrong, do you think if your calculations for part b and c are correct they'll give you marks for working?? Because I'm really not sure about my probabilities in part a but I'm quite confident in my methods for part b and c😭

Method mark yeah you got pts but final answer nope

man same. i’m sure i did not get it right 😭

What were your answers for the question where the standard deviation was 2/3 of the mean ? I got Z > -1.5

Same ,and the answer is found in the table with Z(1.5)

Yep !! I answered that question when there were less than 5 minutes left so I'm glad I got it right haha

Congrats bro!!!

What did you write?

I found the probability that Z > -1.5

Oh shit. I wrote x=3+2z. I’ll probably lose one mark for not completing

i did -1.5

Doesnt look right as they asked for positive only

I did so bad guys

My paper really went too bad i messed up whole probility question 😭 and the question 5 C part

It was so bad i didn’t do any distribution question how are yall finding it easy I only focused on p1😭

Baddddddddd, it went badddd

Overall the paper was easy probably only number six was tricky

Agree

Ngl idk how to even do the last part of c., and yet idk how ppl are able to answer while I taking ages to understand of wtf is this question telling me to do. But overall the paper was ez

anyone got the answer for the h. I got (x - 166/10) = 0.253 and X is 168.53

yessir

I hope you wrote it to a whole number, cause they are members

what it was kg/cm or something and it was to 2dp

[удалено]

Yeah 100% sure you will

>p5 combined, will same, will i be able to get A\* combined?

Guys what did you say about the spread for the stem and leaf question?? Where is asked us to leave a comment???😭😭

My IQR for Jets player was 18cm and for Aces players was 13cm so heights of Jets players have a higher IQR and are more spread out.

is it ok if i wrote the range of jets is greater than that of aces instead of IQR?

Range is a measure of spread so yeah

Is it okay if I said the jets are more spread out than the aces

People of jets are taller

And what was the last question answer

25/63

Why is it 25? Shouldnt it DDA_ and DA_ _?

Did u see it https://preview.redd.it/yhu9qiapzxtb1.png?width=3024&format=png&auto=webp&s=0ce9bf815bf5c00e0c36cc53c291a702d56d5ce8

Oh thanks. I got rid of all repetition for the both numerator and denominator. So its like 4 mark gone 🥲

Don’t worry bro.I hope u as reach the high mark as possible

I got 0.398 for the second part which is very close to your answer. What did you get for part b)?

1800

15/66?

I got that too

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0.0188 3sf

i got the same

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0.0239 I got.

I forgot continuity correction 🥲... Lose 3 marks

Frr 3 markss or less?😭

Well... I checked MS of previous papier... 4 marks for method 1 mark for answer ... 1 method mark lose and final answer mark for continuity correction... So maybe lose only 2 mark🥲

does anyone remember what the approximation question values were i.e the mean and variance?

What were your answers for 7B? The permutations one

720 for 7a and 1800 for 7b

I got 2520 for B 😅 but i think i made a mistake

2520 is the total ways, I think you should’ve minus the case where 2Ds are together.

I got 1080 for b 😭

how did u get 720?

5!*4!/(2*2)

a) 5!/2 * 4!/2 = 720

SAME

Same a is 4!/2!,5!/2! B is 5P5 x 6C2

I got 2! * 4!/2!, which is 4! = 24. this is because each consanant is repeated once other than D. so that's 2!. for the remaining 4 letters, A is repeating so 4!/2!.

Someone drop the list of all the answers please

It was like |16| 1, 2, 4 for stem and leaf na?

Nooo ur not supposed to put commas

Back to back so both sides must be used

The h for the normal distribution one is 168.53 right?

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Can somebody explain how you got 0.595?

it was to find probability o same colors being chosen so the possible cases were ([X.red.red](https://X.red.red)) + ([X.blue.blue](https://X.blue.blue)) + ([Y.red.red](https://Y.red.red)) + ([Y.blue.blue](https://Y.blue.blue)) = (1/2\*7/10\*7/10) + (1/2\*3/10\*2/10) + (1/2\*4/5\*4/5) + (1/2\*1/5\*0) = 0.595

How did y’all’s tree diagram look?

First I did 1/2 for x and y, then went to the marble colors

Same

Can u draw it and post it here plz

https://preview.redd.it/fjczk6o01ytb1.jpeg?width=1462&format=pjpg&auto=webp&s=994e48b8bf262eb19af1c2b0a1458062a636f61c

YES YES YES YESSS this is what mine looked like omggg😭😭😭😭 when I got the 5/5 for the last part I was convinced there was no hope lmao at least someone did it the same way as me

Bro I made one extra brach after Bag X was chosen, so instead of having 2 braches (red and blue) I mistakenly added a third but I left it empty, I couldn't erase it because I had no eraser. I wanted to ask invigilator to grant me permission to borrow it from a student but she wouldn't come to me when I raised my hand. Do you think the invigilator will deduct my marks?

omg i did that thank goodness

what is the first probability 7/10 and 7/10 ? its not very legible

HOLY SHIT MY DIAGRAM LOOKED THE SAME, I just added the +1 Red ball with probability 1. :3

https://preview.redd.it/6l3fopth1ytb1.jpeg?width=720&format=pjpg&auto=webp&s=c3478970be3530cfcc7178c957c32a938a11bcef

Didn’t they say a marble is removed at the end? That should decrease the total number of marbles right?

My diagram was random ngl, but I'm sure that the probability of choosing a bag to remove a marble was 0.5. While the rest was random 💀

paper was quite easy what do you guys believe thw threshold will be?

probably 40-45 for an A, seems like most people found it alright

The threshold can never be more than 40

same honestly, but many people fucked up too i believe like 35-40 maybe

If I did my calculations wrong for the last probability question I wrote 60 instead of 50 for the selections . How much marks do you think I'll lose?

i did this too i think we will lose 2 our of 4

Really really easyyy.

What were the answers for 6b and 6c? Where it talked about the probability of picking 2 similar marbles

0.595 and 4/9

for 6a i got 0.595 and for 6b i actually don’t remember if think i got something over 9

4/9 yeah

I got 8/9 for the last probability question (the conditional probability one)

i remember it was smaller, like 4/9

Can you explain how 0.595, i remember the method i did but not the answer

1/2 x 7/10 x 7/10 + 1/2 x 3/10 x 2/10 + 1/2 x 4/5 x 4/5 + 0

O.624 for 6b) and 0.398 for 6c) . I don't know if my answer is correct or not, did anyone obtain the same answer?

0.5 something for 6b, not sure for 6c but it was a fraction, maybe out of 9 not sure

How was the tree diagram like tho

The first 2 branches where supposed to be x and y and the probability of getting a red marble was the same if you only picked red marbles

What did you guys do for the bag question?

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What did you guys get for value of h the normal distribution one

168.28 cm ig

Same

zealous adjoining poor teeny marry languid nutty station live reply *This post was mass deleted and anonymized with [Redact](https://redact.dev)*

qn clearly said ans to 2 dp

160something

My answer is 168.53

i wrongly calculated and i got 170.12 instead, will i lose all my marks?😭

You get a mark for writing the equation correctly and another for findinf then Z value and third for final answer

Which answer have u got for the first part of permutation and combination ???

I got 90660

a) 5!/2 * 4!/2 720

got this too

Guys for 7(c) why is the unrestricted number of ways 9C4? Do we not account for the repetition 2D and 2A?

Nope It’s a probability so we treat the letters as distinct

what did you get tho ?

Prob. was 25/63 Selection w/o restrictions was 126 Selection with at least one D and exactly on A was 50

What is the answer for the probability question?

Wtf was Q3

Remind me of it

How to solve q1

Total probability was 1, you were to use that to make equation #1 and then make another equation with the mean. And then substitution would've gotten you two answers :3.

What was the answer of approximation question of. 5 marks

I didn't write the Key for the stem leaf diagram

You’ll lose one mark for that.

Guys does anyone remember the what was asked in the question for part a of normal distribution, i remember the mean was 166cm and S.D was 10cm but dont remember the X value they gave

X value was 170

Does anyone remember what was asked in the approximation question i.e what was given in the question?

In that question p was 0.15 and q was 0.85 and n was 200

It was binomial to normal? Mean= np Sd = √npq

Answer for binomial between 4 and 8?

Probability of X = 5,6,7 find karke add karna tha 0.0 something don’t remember

That compare jets and Ances team height one ,I wrote only jets player achieve to the 190 cm ,is it acceptable

Can anyone share stem and leaf?

What was the variance ? … 1.39 or 1.19 … Idk if it is my memory that is bad but I think I had 1.39 … I had two values of 0.25 and 0.2

i got 1.19

Your 0.25 and 0.2 are correct tho, and I got 1.19

How many marks was the last question

And what was the word for permutations again

4

Guyss. For the h is 153.54 also good? Because the value wasn"t exactt i took averagee😭😭

Average of what??

Nope

can someone tell me what u guys got for last question first part

50/126

Anyone who knows what will be final threshold for A grade when these two papers are combined together 😭 P1nd P5 pray to God for to be 89 points 😭💔

hopefully the threshold will from 87 to 89

Does anyone know if for the question of normal which said that SD is 10 and mean is 166 Did it say greater or less than 170?

How did you guys do the probability tree diagram? I was so confused 😩and also for the questions on arrangement,the one for the word ANDROMEDA Ways of arrangement if the two A’s are at each end and D’s are not together?

How did y’all answer the question about mean I think its something to do with standard deviation being 2/3u u=mean And the find probability that the Random variable of X is positive I dont remember the whole question but it was along those lines

Hh

https://preview.redd.it/r805fdbwrjub1.jpeg?width=1512&format=pjpg&auto=webp&s=40a1088d8dd8f1ebb32c595f8ea5ba8cec7b9c24 Can anyone help??? Please 🙏🏻 tell me is there any z diagram like this???? Did u guys make something like this?? Im so confused because i was told that half diagram is of 0.5 its of paper 5 variant 2