# I need help! Statistics/ probability

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#1
So I need help with my assignment. I do not know how to do this, and I have until Friday to answer.

Here is the assignment:

You randomly select 10 stocks that are included in the OBX index. This index consists of 25 stocks. It turned out that 20 of these shares increased in value the following year.
What is the probability that the value increased on all 10 shares that you selected?
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1 month ago
#2
Find the probability of how shares increasing in value (based on the information given)

then multiply with the number of stocks u picked over the total number of stocks
Last edited by Frozetman; 1 month ago
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1 month ago
#3
(Original post by Frozetman)
....
As per the forum guidelines (sticky at the top), its better to give hints rather than "solutions".
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1 month ago
#4
(Original post by mqb2766)
As per the forum guidelines (sticky at the top), its better to give hints rather than "solutions".
Sorry my bad I’ll edit the post
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1 month ago
#5
(Original post by Frozetman)
Sorry my bad I’ll edit the post
Ok. Its not really correct though.
Last edited by mqb2766; 1 month ago
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1 month ago
#6
(Original post by mqb2766)
Ok. Its not really correct though.
what the answer, how would u put it then
Last edited by Frozetman; 1 month ago
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1 month ago
#7
(Original post by Frozetman)
what the answer, how would u put it then
The problem is similar to picking coloured balls out of a bag, without replacement. Its slightly unclear about whether its with or without replacement, i.e. whether the selected stocks are distinct - though it would be strange if they were not distinct.

But as the OP has said its for their assignment, its better to let them post their attempt first.
Last edited by mqb2766; 1 month ago
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1 month ago
#8
(Original post by mqb2766)
The problem is similar to picking coloured balls out of a bag, without replacement. Its slightly unclear about whether its with or without replacement, i.e. whether the selected stocks are distinct - though it would be strange if they were not distinct.

But as the OP has said its for their assignment, its better to let them post their attempt first.
Thinking about it more I actually think this is binomial expansion.
Last edited by Frozetman; 1 month ago
1
1 month ago
#9
(Original post by Frozetman)
Thinking about it more I actually think this is binomial expansion.
If it is with replacement then the scenario is the same as a binomial distribution.
Without replacement, then the numbers are a bit different.

But its best to let the OP attempt the problem first.
Last edited by mqb2766; 1 month ago
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#10
(Original post by Frozetman)
Find the probability of how shares increasing in value (based on the information given)

then multiply with the number of stocks u picked over the total number of stocks
I tried but something seemed off. If you are able to, can you give me the answer, with an explanation (equation)?
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1 month ago
#11
(Original post by Juz13)
I tried but something seemed off. If you are able to, can you give me the answer, with an explanation (equation)?
The forum guidelines are to upload what you tried,
https://www.thestudentroom.co.uk/sho....php?t=4919248
not to expect solutions.
Last edited by mqb2766; 1 month ago
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#12
(Original post by mqb2766)
The forum guidelines are to upload what you tried,
https://www.thestudentroom.co.uk/sho....php?t=4919248
not to expect solutions.
I understand that, dont get me wrong. I've done all the other task in this assignment, however I'm struggling with this one. Which is the last of all the tasks, hence me asking for more in depth help.
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1 month ago
#13
(Original post by Juz13)
I understand that, dont get me wrong. I've done all the other task in this assignment, however I'm struggling with this one. Which is the last of all the tasks, hence me asking for more in depth help.
What have you tried / your thoughts?
If you've done other similar questions, you should be able to make a reasonable attempt.
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1 month ago
#14
Try thinking about if you only chose 1 stock.

What is the probability that it was one that increased?

Now think about two stocks. What is the probability that both increased?

If you can see these answers, how would you extend the logic to 10 stocks?
Last edited by chazwomaq; 1 month ago
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1 month ago
#15
(Original post by Juz13)
I tried but something seemed off. If you are able to, can you give me the answer, with an explanation (equation)?
Like I said the first method I put was wrong.

Think about what u can work out and what you've already learnt.

(Original post by chazwomaq)
Try thinking about if you only chose 1 stock.

What is the probability that it was one that increased?

Now think about two stocks. What is the probability that both increased?

If you can see these answers, how would you extend the logic to 10 stocks?
This puts it very clearly what u have to do.

But if u know there is a very quick way tto do a question like this
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