Statistics Question Urgent HelpWatch

#1
Doing an S2 question and I don't get this
Biased 4 sided spinner can only land on 1,2,3,4
Random Variable X is the number that the spinner lands on after a single spin
P(X=q) = P(X=q+2) for q=1.2
Given P(X=2) = 0.35

(a) Find the complete probability distribution of q

(b) spinner spinned 50 times
find probability more than half land on number 4

The random variable
12
Y= ----
X
Find P (Y-X<=4)
Find P( Y - X less or equal to 4)
0
#2
bump
0
#3
bump
0
#4
bump
0
1 year ago
#5
(Original post by Pakora99)
bump
Insufficient information to resolve the problem - unless it's to be left in terms of a parameter.

0
#6
(Original post by ghostwalker)
Insufficient information to resolve the problem - unless it's to be left in terms of a parameter.

sorry bout that forgot to add this bit Given P(X=2) = 0.35
updated it at the top as well
0
1 year ago
#7
(Original post by Pakora99)
sorry bout that forgot to add this bit Given P(X=2) = 0.35
updated it at the top as well
From the question, then:

P(X=2) = P(X=4) = 0.35

P(X=1) = P(X=3) = ?

And use the fact that the total probability must be 1, to work out the unknown value.
0
#8
(Original post by ghostwalker)
From the question, then:

P(X=2) = P(X=4) = 0.35

P(X=1) = P(X=3) = ?

And use the fact that the total probability must be 1, to work out the unknown value.
P(X=2) = P(X=4) = 0.35 how do you know 2 and 4 are related
0
#9
(Original post by ghostwalker)
From the question, then:

P(X=2) = P(X=4) = 0.35

P(X=1) = P(X=3) = ?

And use the fact that the total probability must be 1, to work out the unknown value.
so P(X=1) = 0.15
P(X=3) =0.15
0
1 year ago
#10
(Original post by Pakora99)
P(X=2) = P(X=4) = 0.35 how do you know 2 and 4 are related
Question tells you.

"P(X=q) = P(X=q+2) for q=1.2"

Setting q=2

P(X=2) = P(X=4)
1
#11
(Original post by ghostwalker)
Question tells you.

"P(X=q) = P(X=q+2) for q=1.2"

Setting q=2

P(X=2) = P(X=4)
Ahh Thank You!!!
0
1 year ago
#12
(Original post by Pakora99)
so P(X=1) = 0.15
P(X=3) =0.15
Yes.

Can you do part b? If not, what distribution do you thnk it is?
0
#13
(Original post by ghostwalker)
Yes.

Can you do part b? If not, what distribution do you thnk it is?
Looks like binomial distribution so I've done
1-P(X<25) = P(X>25)
1-P(X{less or equal} 25) = P(X>25)
let x be 0.35
0.989956 for P(X<25)
1-0.989956=0.01
not too sure on this bit if I've done It right
0
1 year ago
#14
(Original post by Pakora99)
Looks like binomial distribution so I've done
1-P(X<25) = P(X>25)
1-P(X{less or equal} 25) = P(X>25)
Yes, should be

let x be 0.35
p=0.35
Probability of success on a single spin.

0.989956 for P(X<25)
1-0.989956=0.01
not too sure on this bit if I've done It right
Yep.
0
#15
(Original post by ghostwalker)
Yes, should be

p=0.35
Probability of success on a single spin.

Yep.
y=12/X
FindP(Yâˆ’Xâ‰¤4)
I was thinking about finding in the 50 spins where X is less or equal to 4
But how would I do the Y bit?
Sorry about no latex I can't figure out how to use it
0
1 year ago
#16
(Original post by Pakora99)
y=12/X
FindP(Yâˆ’Xâ‰¤4)
I was thinking about finding in the 50 spins where X is less or equal to 4
But how would I do the Y bit?
Sorry about no latex I can't figure out how to use it
The 50 spins don't come into it, unless there's something you've not posted.

You're only dealing with 1 spin, with r.v. X

So, you just need to check when . There are only 4 values, with their corresponding probabilities.
0
#17
(Original post by ghostwalker)
The 50 spins don't come into it, unless there's something you've not posted.

You're only dealing with 1 spin, with r.v. X

So, you just need to check when . There are only 4 values, with their corresponding probabilities.
If P(X<=4) then
all values less than it is 0.65 and including is equal to 1
cuz P(X=4) is 0.35 all values less is 0.65
0
1 year ago
#18
(Original post by Pakora99)
If P(X<=4) then
all values less than it is 0.65 and including is equal to 1
cuz P(X=4) is 0.35 all values less is 0.65
OK, I think I know what you mean, but so what!

You're interested in P(12/X-X<= 4), not P(X<= 4)

You need to evaluate that function over the domain of X, i.e. 1,2,3,4. And check if that function is <=4.
0
#19
(Original post by ghostwalker)
OK, I think I know what you mean, but so what!

You're interested in P(12/X-X<= 4), not P(X<= 4)

You need to evaluate that function over the domain of X, i.e. 1,2,3,4. And check if that function is <=4.
I don't know where to start
0
1 year ago
#20
(Original post by Pakora99)
I don't know where to start
IF X=1, then (12/X)-X = (12/1)-1 = 11.

This is >4, so we don't include P(X=1) in the sum of the probability.

Etc.
0
X

new posts
Back
to top
Latest
My Feed

Oops, nobody has postedin the last few hours.

Why not re-start the conversation?

see more

See more of what you like onThe Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

University open days

• Regent's University London
Thu, 19 Sep '19
• Durham University
Fri, 20 Sep '19
• Loughborough University
Fri, 20 Sep '19

Poll

Join the discussion

Rock (188)
23.98%
Pop (191)
24.36%
Jazz (30)
3.83%
Classical (46)
5.87%
Hip-Hop (148)
18.88%
Electronic (53)
6.76%
Indie (128)
16.33%