1. X and Y are independent distributed Gaussian (0, 1) random variables.(a) Find the CDF and PDF of W = X2 + Y2.Hint: use polar coordinate system to simplify the integration(b) Name the RV W and its parameter.
6. (4%) A professor pays 250 won for each ppt slide error made in lecture to the student who points out the error. In a career of n years filled with ppt errors, the total amount in Won paid can be approximated by Yn ~ Gaussian(40,000n, 1,000,000n). What is the probability that Y20 exceeds 100 man (1,000,000) won? How many years n must the professor teach in order that P[Yn>1,000,000]>0.99?Let 1k = 1000Since E[Y20] = 40k(20) = 800k and Var[Y20] = (1k)2(20), we can write..<중 략>
2. You have a database of emails.• 60% of those emails are spamo 80% of those emails that are spam have the word "100% free!"o 20% of those emails that are spam don't have the word "100% free!"• 40% of those emails aren't spamo 10% of those emails that aren't spam have the word "100% free!"o 90% of those emails that aren't spam don't have the word "100% free!"What is the probability that an email is spam if it has the word "100% free!"?