Exponential Distribution Question

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Discussion Overview

The discussion revolves around a problem involving the exponential distribution, specifically focusing on the concept of memorylessness in relation to the expected remaining life of a tiger given its current age. Participants explore theoretical aspects of the exponential distribution and its properties.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant presents a problem regarding the expected remaining life of a tiger that is 10 years old, given that its life follows an exponential distribution with a mean of 15 years.
  • Another participant seeks clarification on the concept of 'memorylessness' and asks which distributions possess this property.
  • A participant defines memorylessness, stating that the probability distribution of the remaining time until an event occurs remains unchanged regardless of the time that has already passed, suggesting that the expected remaining life is 5 years.
  • A follow-up comment reiterates the definition of memorylessness and questions what this implies for forward-looking expectations, while also inquiring about the distributions that exhibit this property.

Areas of Agreement / Disagreement

Participants express differing views on the expected remaining life of the tiger, with some suggesting it is 5 years based on the memorylessness property, while the overall consensus on the correct answer remains unresolved.

Contextual Notes

The discussion does not clarify the assumptions underlying the problem, nor does it resolve the mathematical implications of the memorylessness property in this context.

Caution
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Hi all,
Can anyone teach me this problem ? Thanks

The life of a tiger is exponentially distributed with a mean of 15 years.If a tiger is 10 years old, what is the expected remaining life of the tiger?

A 5 years
B 10 years
C 15 years
D Longer than 15 years
 
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Can you tell me your understanding of 'memorylessness'? What distributions have this property and what does it mean?
 
StoneTemplePython said:
Can you tell me your understanding of 'memorylessness'? What distributions have this property and what does it mean?

It means the probability distribution of the remaining time until the event occurs always is the same, regardless of how much time (s) already has passed. So I'm guessing the answer is 5?
 
Caution said:
It means the probability distribution of the remaining time until the event occurs always is the same, regardless of how much time (s) already has passed. So I'm guessing the answer is 5?

so if the probability distribution is the same whether 0 years have passed or 7 years have passed, then what does that tell you about forward looking expectations?

Also do you know which distributions exhibit memorylessness? (There are only 2...)
 

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