MATH 337: Assignment 1
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MATH 337: Assignment 1
2021
1. (a) Show that eα ≥ 1 + x for all real values of x.
(b) Assuming that a year has 365 days, show that in a group of 23 people, the probability that at least two people have the same birthday is greater than 1/2. [Hint: first calculate the probabil- ity that in a group of n people, no two share the same birthday using (a).]
2. Prove that
〇 = 一 tanh³ … ╱ ← ,
where ∆ = b〇 一 4ac > 0.
3. Prove that for |x| < 1,
兰 k〇x亿 ³ … = 1 + x
亿2←
4. Let X be a random variable with geometric distribution having pa- rameter p. That is, P (X = k) = p(1 一 p)亿 ³ … . Show that
E(X〇 ) =
2 一 p
p〇 .
5. Let X be a random variable with the uniform distribution on the interval [a, b]. That is, X has density function fx given by
fx (x) = ,0(1)/(b 一
Show that X has mean (a + b)/2 and variance (b 一 a)〇 /12.
6. If X is a random variable with density function fx (y) = e³g/9 , y > 0,
then X has variance θ〇 .
7. If X and Y are random variables with the Poisson distribution of parameters λ and τ respectively, show that X + Y is again Poisson with parameer λ + τ .
8. If X is a random variable with density function fx (y) = ya ³ … e ³g/8 , y > 0,
show that Var(X) is αβ〇 .
9. Let Γ(x) denote the Γ-function. Show that Γ(1/2) = ′π .
10. Let X be a random variable with the normal distribution e³α2 /〇 .
Show that Var(X)=1.
2022-04-23