probabilities.....

eddy2017

eddy2017

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hi, like i mentioned i am reading some probability problems. here is one that i found. there is no answer on the article. i would like to enlist your help to solve it.

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these are the questions:
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any hints?
thanks,
eddy
a) The sample space is the entire list of simple events: 0, 1, 2, 3, 4, 5.
 
p(number of CDs sold >3) = p(exactly 4 CDs sold) + p(exactly 5 CDs sold)
 
Jomo and the magnificent feline are both correct.

The cat’s point, as it strokes its whiskers in understandable self-satisfaction (self-satisfaction being a lamentable failing of felines in general as demonstrated recently by my daughter-in-law’s cat as it strode proudly across the lawn with a vole dangling from its jaws as thought it were a lion on the veldt with a dead wildebeest), is that, if you add up the probabilities that you are given, you will see that they sum to 1 exactly so anything greater than five sales a day is impossible. So the list of elements in the sample space contains how many elements? What are those elements in the list?

Jomo, though obviously not as show-offy as a feline, has also given a correct answer. When can you add probabilities as jomo has done?
 
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Harry_the_cat said:
According to the model (where the probs add up to 1), the prob of selling 6 CDs is 0.
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Okay, i got that. we sum it all up and we get 1. I got it. But why is the probability of selling 6 cds is 0 at that point ?.
Jeff said this in my previous thread:
"The probability of an event can be zero. What does that mean? The probability of an event can be one. Why?
 
eddy2017 said:
Okay, i got that. we sum it all up and we get 1. I got it. But why is the probability of selling 6 cds is 0 at that point ?.
Jeff said this in my previous thread:
"The probability of an event can be zero. What does that mean? The probability of an event can be one. Why?
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i have read this and seems logical, but i would like a practical example if you have the time.

'Tautologically, zero-probability events are events whose probability is equal to zero.
P(E) =0
Can anyone give an example?
 
Do you agree with this
Chance is also known as probability, which is represented numerically. Probability as a number lies between 0 and 1 . A probability of 0 means that the event will not happen.

An example

For example, if the chance of being involved in a road traffic accident was 0 this would mean it would never happen. You would be perfectly safe. A probability of 1 means that the event will happen. If the probability of a road traffic accident was 1 there would be nothing you could do to stop it. It will happen
 
eddy2017 said:
i have read this and seems logical, but i would like a practical example if you have the time.

'Tautologically, zero-probability events are events whose probability is equal to zero.
P(E) =0
Can anyone give an example?
Click to expand...
The probability that you will have dinner next Wednesday with a unicorn is zero. Therefore your having dinner with a unicorn next week is a zero-probability event.
 
JeffM said:
The probability that you will have dinner next Wednesday with a unicorn is zero. Therefore your having dinner with a unicorn next week is a zero-probability event.
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Okay got it.
Jeff when is probability equal to 1?
 
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eddy2017 said:
Okay got it.
Jeff when is probability equal to 1?
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Got it now after reading this. One of the questions here ( the one that Ms Harriet answered had to do with when P = 1)
Because,

"The sum of the probabilities of all outcomes must equal 1 . If two events have no outcomes in common, the probability that one or the other occurs is the sum of their individual probabilities. The probability that an event does not occur is 1 minus the probability that the event does occur.
 
The probability that the sum of two decimal digits is an integer is 1.

You may think that this is trivial, but notice it is a falsity if we replace the word “sum” with the word “quotient.”

PS: The best short discussion (deep but elegantly written) in my opinion about the meaning of probability is this

 
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JeffM said:
The probability that the sum of two decimal digits is an integer is 1.

You may think that this is trivial, but notice it is a falsity if we replace the word “sum” with the word “quotient.”
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No it is not trivial at all. In fact, you saying that has put it in crystal clear perspective for me. Thanks.
 
The probability that you roll a die and get a 7 is 0. It simply will not happen.
The probability that you roll a die and get 1, 2, 3, 4, 5, 6, 7 or 8 is 1
 
After reading math info online that seems to be intended to go over people's it is a real breath of fresh air to read your explanations. You make it so clear!. Tx
 
eddy2017 said:
After reading math info online that seems to be intended to go over people's it is a real breath of fresh air to read your explanations. You make it so clear!. Tx
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Eddy If you can read Poincare and get something from him, the problem is not that things are over your head. Rather the problem is that the vocabulary and notation are unfamiliar.
 
JeffM said:
Eddy If you can read Poincare and get something from him, the problem is not that things are over your head. Rather the problem is that the vocabulary and notation are unfamiliar.
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Right, that is it, I know. Reading math is doing me a world of good. I will be asking you when something gets too arcane for me. Reading and doing exercises helps. I agree concepts are best seen in action but they are necessary. Clear the path for a better grasp. Thanks for your comments. Much appreciated.
Julius Henri Poincaré. Quite a man and a mind!. His contribution to the modern chaos theory, wow!. If i had someone like you at my fingertips i would be reading and asking the whole day away!. Have a restful night, professor.
 
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