How Do You Calculate the Probability in an Exponential Distribution?

In summary, the conversation discusses calculating the probability P(Y > 1) for a random variable Y with an EXP(2) distribution. The CDF for this distribution is used, which is defined as P[X \le x]=1-e^{-\lambda x}. By plugging in the appropriate values, it is determined that P(Y > 1) is approximately 0.1353.
  • #1
das1
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Help?

Suppose the random variable Y has an EXP(2) distribution. What is P(Y > 1)? (Round to four decimal places as appropriate.)
 
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  • #2
das said:
Help?

Suppose the random variable Y has an EXP(2) distribution. What is P(Y > 1)? (Round to four decimal places as appropriate.)

Are you allowed to use the CDF for this distribution or should you calculate this purely from the pdf? Either way you'll need to also use this fact: \(\displaystyle P[Y>2]=1-P[Y \le 2]\)
 
  • #3
I don't think there are any restrictions on what functions I can or can't use
 
  • #4
das said:
I don't think there are any restrictions on what functions I can or can't use

Ok, then this should be very useful. For the exponential distribution, the CDF is the following: \(\displaystyle P[X \le x]=1-e^{-\lambda x}\). How can you use this to answer your question?
 
  • #5
So would I plug in 1 for x and 2 for λ?
Then we would get 1-e^(-2*1)? Which is .8467 but we'd actually want 1-.8467 again because we're looking for P(Y > 1) right? So about .1353?
 
  • #6
That looks good to me! (Yes)
 

FAQ: How Do You Calculate the Probability in an Exponential Distribution?

What is the Exponential Distribution?

The Exponential Distribution is a probability distribution that describes the time between events in a Poisson process. It is used to model situations where events occur continuously and independently at a constant average rate.

What are the key characteristics of the Exponential Distribution?

The Exponential Distribution has two key parameters: the rate parameter (λ) and the mean (μ). The rate parameter determines the average rate of events occurring, while the mean represents the expected time between events. It is a continuous distribution with a skewed right shape and ranges from 0 to infinity.

How is the Exponential Distribution different from other distributions?

The Exponential Distribution is unique because it models the time between events, rather than the number of events in a given time period. It also has a constant failure rate, meaning the probability of an event occurring in a specific time interval does not change over time.

What are some real-world applications of the Exponential Distribution?

The Exponential Distribution is commonly used in fields such as engineering, finance, and healthcare. It can be used to model the time between equipment failures, the time between customer arrivals, and the time between medical treatments. It is also used in reliability analysis and to study the lifespan of products.

How is the Exponential Distribution calculated?

The probability density function (PDF) for the Exponential Distribution is f(x) = λe^-λx, where λ is the rate parameter and x is the time between events. The cumulative distribution function (CDF) is F(x) = 1 - e^-λx. These equations can be used to calculate probabilities and make predictions about future events.

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