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# How did you find S1? watch

1. (Original post by John714)
what is the S.D of Q4
i got summin like 40.1 or summin! u?
2. (Original post by SAM*)
i got summin like 40.1 or summin! u?

huh? question 4? i swear that ws 4 da question 5 normal dist
3. normal distribution s.d i got something like 83.1
4. (Original post by Godmaster)
huh? question 4? i swear that ws 4 da question 5 normal dist
sorry may well ave been, i tink i got 83. summin or another for Q4
5. s1 was soooooooo easyyyyy!!!!
6. The graph - used broken scale

Normal distribution - 0.3% (0.003) anybody?

Discrete random variables a = 0.4 b=0.1, P(0<X<1.5) = P(1) = ?

Last ques c) P(C) = 0.625

1) 7/12

2) r = 0.87. a = around 230. b = 1.44

7. Edexcel S1 6683/01

1. 1/4 (9 combinations of getting greater than 5 (two twos and 3 threes ont the dice, each with a 1/36 chance of being rolled)

First two with each 3: 3 combs
Second Two with each: 3 combs
First three with other two threes: 2 combs
Second three with the last 3: 1 comb = 9 combs = 9/36 = 1/4

2. PMCC somewhere around 0.84 / 884

Regression line: c = 317 + 1.43h

Strong Positive linear correlation between height / confidence

Estimate for height of 180 cm = 574.4

Values must give confidence bewteen 500 and 600 so values of around 128 cm - 198 cm

3 a= 0.4
b = 0.1

Variance proved to be 1.41 as E(x squared) = 4.3

Variance of (2X + ?) = 4 Var X = 6.8

4 Back to back stem and leaf preety easy

Median and quartiles around 16, 17, 18
Mode of 1st Group: 18 Mode of Second Group: 15

IQR of a: 3 or 2? IQR of B: 3 or 2?

Didnt really answer comparing, but I think first group had higher average attendence tham second group

5 X-N(90, sigma Squared)
P(X>125) = 0.2
P (Z > 125 - 90 / Sigma) = 0.2
P (Z < 125 - 90 / Sigma) = 0.8

Iota (125 - 90 / sigma) = 0.8
Look in table. closest is 0.84

so: 125 - 90 / sigma = 0.84
35 = 0.84 sigma
Sigma = 125/3

Other one just use sigma squared from above, probablility something like
1- 0.9406 = 0.0594

C: I said not suitable, as the original normal districution model was based on being able to use the facilities for as long as they wished, girl in question only had two hours

6 Couldnt do parts a: (P A given C) and part C (P of C)

Thought part B (A union B) = 0.6 as P(A U B) = P(A) + P(B) + P(A n B)

As A and B are mutually exclusive, P(A n B) = 0 so P(A U B) = 0.4 + 0.2 = 0.6

Hopefully dropped a maximum of 7 marks, which hopefully should be an A

Predicted Boundries:

A = 80 UMS = 64
B = 70 UMS = 57
C = 60 UMS = 50
D = 50 UMS = 44
E = 40 UMS = 38

Paper I think a little easier than last year, so slightly higher grade boundries
8. oh and ques 2 SD around 1.16
9. (Original post by MBR50)
The graph - used broken scale

Normal distribution - 0.3% (0.003) anybody?

Discrete random variables a = 0.4 b=0.1, P(0<X<1.5) = P(1) = ?

Last ques c) P(C) = 0.625

1) 7/12

2) r = 0.87. a = around 230. b = 1.44

hey i got all of that!
normal distribution s.d i got something like 83.1

huh:s how can dat b doe remeber onli 20% are over 125minutes

wen the range between the mean and SD was around 131 cos i added them which looks about right
11. OK I need to know this...

For the last question, did you get that A and B were mutually exclusive, and that B and C were independant?

i.e. Is this diagram wrong? If yes, what should it have been?

See Attachment.
Attached Files
12. Doc1.doc (19.0 KB, 161 views)
13. hey I got the venn diagram with C in the middle. but A and B not touching
14. (Original post by MBR50)
hey I got the venn diagram with C in the middle. but A and B not touching
yeah thats right
OK I need to know this...

For the last question, did you get that A and B were mutually exclusive, and that B and C were independant?

i.e. Is this diagram wrong? If yes, what should it have been?

See Attachment.
My diagram is the same, but I think is wrong.
16. i got 5/12 on number one
17. i got the following Venn diagram see attachment! how were we mean to know whether B and C were related i got well confused, if some one can possibly show me wot it was meant to loook like?
Attached Files
18. venn.doc (23.5 KB, 131 views)
19. I got 7/12 because it was greater and equal to 5, right?
20. Basically A and B DO NOT TOUCH, C Touches both A and C as P(B n C) is not 0, as this is not defined.
21. yeah it was
still got 5/12 though
someone else had the same as you

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