S1 ial exam - january 2015

OP

It was good..what did u do for that question in which they asked to find the value of a and b between which the middle 95% of the data lies ?!?!

Reply 3

exztra

1

Ah dnt ask me that! I figurd out sth abt it jst bfore the xm ends nd cudnt cmplt it :frown:

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Reply 4

exztra

1

Any more questns? Did u find it easy, ok or hard? Or is it only me who thought tym was vry less acrdng to questn

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Reply 5

OP

Can u temme what u would do for that if u had more time..
And umm I found it alright.. time was ok for me.. hoping for a good grade :smile:

Reply 6

ecy98

Original post by sparrow_12

It was good..what did u do for that question in which they asked to find the value of a and b between which the middle 95% of the data lies ?!?!

since P(a<x<b)=0.95 i did P(x<b)=0.975 and used the values of mean and standard deviation like alway.. p(Z<(b-μ/σ)=0.975 and used the big table of values for φ(z) approximately 0.975 to find the value of b

Reply 7

gdunne42

21

I am not an official spokesperson but Arsey is a UK teacher who will not have any students taking this series of exams.. So I suspect there is no urgency to produce any model answers.

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(edited 9 years ago)

Reply 8

Original post by ecy98

since P(a<x<b)=0.95 i did P(x<b)=0.975 and used the values of mean and standard deviation like alway.. p(Z<(b-μ/σ)=0.975 and used the big table of values for φ(z) approximately 0.975 to find the value of b

What was the value for k in the last question? and what was the standard deviation?? Does anyone remember???

Reply 9

ThatAsianKid

Original post by mtareq24

What was the value for k in the last question? and what was the standard deviation?? Does anyone remember???

Im not sure if i remember correctly
But k was 101.4
And s.d was 4.75

Reply 10

OP

K was 101.4 ish.. and standard deviation was 4.something.. can't remember :/

Reply 11

asrar3284

Wasn't k the upper quartile?
Does anybody remember their answers to 1 d and e? P(finding two odds) and (sum of numbers is 6| they're odd) I mean.

Reply 12

Original post by ThatAsianKid

Im not sure if i remember correctly
But k was 101.4
And s.d was 4.75

Bingo!!

Reply 13

Original post by asrar3284

Wasn't k the upper quartile?
Does anybody remember their answers to 1 d and e? P(finding two odds) and (sum of numbers is 6| they're odd) I mean.

Yes it was the upper quartile
And 1d was 0.38** and I forgot 1e

Reply 14

asrar3284

alright. How'd you get 0.38?
like 1d involved finding the probability of finding 2 odds and there were 3 numbers- 1, 3 and 5.
Doesn't that mean that there are six possible outcomes? (1,3; 3,1, 1,5; 5,1; 3,5 and 5,3)
i did 2*P(1 and 3) + 2*P(1 and 5) + 2*P(3 and 5) and got 0.2...

Reply 15

asrar3284

Wasn't k the upper quartile?
Does anybody remember their answers to 1 d and e? P(finding two odds) and (sum of numbers is 6| they're odd) I mean.

Reply 16

ABHM17

Original post by asrar3284

alright. How'd you get 0.38?
like 1d involved finding the probability of finding 2 odds and there were 3 numbers- 1, 3 and 5.
Doesn't that mean that there are six possible outcomes? (1,3; 3,1, 1,5; 5,1; 3,5 and 5,3)
i did 2*P(1 and 3) + 2*P(1 and 5) + 2*P(3 and 5) and got 0.2...

there's also the probability of it being two 1s, 3s or 5s :smile:

Reply 17

OP

I did the same.. :smile:

Reply 18

ABHM17

I think it was the lower quartile and NOT the upper quartile as P(W<k)=3P(W>K) and if it was the upper quartile, three times the upper quartile would give you the 225th percentie, which is illogical, however if it was the lower quartile, three times the lower quartile would be the upper quartile ans since there is no skewness the probability of the upper quartile is equal to the probability of the lower quartile.

Reply 19