Determine what value of a allows for largest probability

In summary, the student is trying to find the value of a which produces a PDF with the largest probability of random variable 'x' falling within two standard deviations either side of the mean.
  • #1
Saracen Rue
150
10

Homework Statement


There are two possible solutions for 'a' for which ##f(x)=|x^x-x^a|## is a probability density function. Determine the value for a which produces a PDF with the largest probability of random variable 'x' falling within two standard deviations either side of the mean.

Homework Equations


Just the rules to do with determining if function is a PDF using integrals as well as finding the mean, variance and standard deviation.

The Attempt at a Solution


I'm honestly at a loss here. There's no way to find the definite integral of this function meaning we need to integrate over a set interval. I calculated the x-intercepts to be 1 and a. I tried getting my calculator to solve (for a) ##∫_0^1f(x)dx=1## and ##∫_0^af(x)dx=1##, both individually and simultaneously, but my calculator kept giving me an error. I'm really not sure what to do here - is there a way to do this manually that I don't knoe about? Any help is greatly appreciated :)
 
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  • #2
As first step I would try to numerically estimate where these values of a are.
I found one so far, I'm not so sure where to look for the other one.
 
  • #3
mfb said:
As first step I would try to numerically estimate where these values of a are.
I found one so far, I'm not so sure where to look for the other one.
Thank you for your help - I had considered just brut forcing it by au substituting different values of a in but I had assumed there was an easier way to do it. I used an online graphing calculator to hell me visualise what was going on and to know where to look for the values of a. If you wouldn't mind could you please look over my working out for this? Here's the link: https://www.desmos.com/calculator/68gbrixyqf
Note, I defined to different functions for each value of a while I was working this out to keep better track of things. I very much appreciate you spending your time to help :)
 
  • #4
Maybe the whole question asks for a numerical analysis. Just by eye I'm quite sure I know which one has a larger integral within 2 standard deviations, but that is not a very mathematical approach.
 

1. What does "value of a" refer to in this question?

In this context, "value of a" refers to a specific numerical value that is used in a mathematical calculation to determine the largest probability.

2. How is the largest probability determined?

The largest probability is determined by using a mathematical formula or equation that takes into account the value of a and other relevant variables.

3. Is there a universal value of a that will always result in the largest probability?

No, the value of a that allows for the largest probability will depend on the specific context and variables involved in the calculation.

4. Can you provide an example of how the value of a affects the probability?

For example, in a coin toss experiment, the value of a would refer to the number of times the coin is flipped. As the value of a increases, the probability of getting heads or tails should approach 0.5 (assuming a fair coin).

5. Are there any limitations or assumptions when determining the value of a for the largest probability?

Yes, there may be limitations or assumptions depending on the specific problem or experiment being studied. For example, the probability calculation may assume that all outcomes are equally likely or that the variables involved are independent.

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