Solve the probability distribution and expectation problem

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The discussion revolves around finding a more efficient method for solving a probability distribution and expectation problem. One participant suggests that calculating the probability of Y=2 by subtracting the probabilities of Y=0 and Y=4 from 1 is a quicker approach. However, concerns are raised about potential errors in this method, as mistakes in calculating Y=0 and Y=4 would directly impact the result for Y=2. An alternative method of finding each probability independently and verifying that their total equals 1 is recommended for accuracy. The conversation emphasizes the balance between efficiency and reliability in probability calculations.
chwala
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Homework Statement
See attached
Relevant Equations
understanding of probability distribution concept...
This is the problem;

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Find my working to solution below;
1635598109409.png

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find mark scheme solution below;

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I seek any other approach ( shorter way of doing it) will be appreciated...
 
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chwala said:
Homework Statement:: See attached
Relevant Equations:: understanding of probability distribution concept...

shorter way of doing it
It would have been quicker to have found the probability of Y=2 by subtracting the other two probabilities from 1. I don't see any other shortcuts.
 
haruspex said:
It would have been quicker to have found the probability of Y=2 by subtracting the other two probabilities from 1. I don't see any other shortcuts.
That's true, but it could pose problem to a student who may have made a mistake on say finding wrong values of ##Y=0 ##& ##Y=4##, ...if you get what I mean... this error would consequently affect the value of ##Y=2##.
Finding the values of ##Y## indepedently and then checking whether their total sum is ##1## is more concrete...
 
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First, I tried to show that ##f_n## converges uniformly on ##[0,2\pi]##, which is true since ##f_n \rightarrow 0## for ##n \rightarrow \infty## and ##\sigma_n=\mathrm{sup}\left| \frac{\sin\left(\frac{n^2}{n+\frac 15}x\right)}{n^{x^2-3x+3}} \right| \leq \frac{1}{|n^{x^2-3x+3}|} \leq \frac{1}{n^{\frac 34}}\rightarrow 0##. I can't use neither Leibnitz's test nor Abel's test. For Dirichlet's test I would need to show, that ##\sin\left(\frac{n^2}{n+\frac 15}x \right)## has partialy bounded sums...