/sci/ - Science & Math

>>11800642
No. Consider for instance, that pic related is the face of /sci/. Do you expect someone with a face like this to be good at math?

>>11800646
looks like me desu

>>11800642
Yes, but I don't speak Sardine

okay, I've tried:
we have two jointly distributed random variables, X and Y, with a joint density function you see at top.

a) calculate the probabilities
i) P(X =< 2, Y =< 1) ii) P (Y >= 1 )

b) estimate covariance (X,Y)

c) estimate the mean (?) E( e^X+Y)for the random variable e^X+Y

d) probability density function for the random variable x|y=b for a undefined number b with 0 =< b =< 2

dii) decide the b-value which gives the mean (? expectancy?) E(X|Y=b)=2

nei, vi er retarder

det e bare å integrer

>>11800668
a)
i)
[eqn] P(X \leq 2, Y \leq 1) = \int_0^2 \int_0^1 f(x,y) dy dx [/eqn]
ii)
[eqn] P(Y \geq 1) = \int_0^5 \int_1^2 f(x,y) dy dx [/eqn]
b)
[eqn]E(X) = \int_0^5 \int_0^2 x f(x,y) dy dx \\
E(Y) = \int_0^5 \int_0^2 y f(x,y) dy dx \\
E(XY) = \int_0^5 \int_0^2 x y f(x,y) dy dx \\
Cov(X,Y) = E(XY) - E(X) E(Y) [/eqn]
c)
[eqn]E(e^{X+Y}) = \int_0^5 \int_0^2 e^{x+y} f(x,y) dy dx [/eqn]
d)
i)
[eqn] f_{X|b}(x) = \frac{f(x,b)}{\int_0^5 f(t,b) dt}
[/eqn]
ii)
[eqn] 2 = E(X|Y=b) = \int_0^5 x f_{X|b}(x) [/eqn]
Solve for b.
I assume you know enough Calculus to calculate those basic integrals yourself.

>>11800642
Det der er enkelt, bare les i boka om joint distributions i 40 min maks så er det bare å følge oppskrift/plugge inn. Håper ikke du er ved UiO.

>>11800642
fuck off brainlet, with your first year math homework

do it yourself or you will stay a retard forever

>>11800839
I've taught enough probability to know that many students think its ok to forget everything about calculus in this class.