Recent content by annie122

i thought if A is 3x5, the columns of A must be linearly dependent, since the rank is at most 3, and the rank is the number of linearly independent columns in A. but there are 5 columns in A, so the columns of A must be linearly dependent :/

i was given a table for calculating joint and marginal distribution. then i was asked if the variables are positively correlated or not. i know what positive correlation is, but how do i determine that from a table?

Re: two probabilities question thanks, I'm cleared now :)

thanks, i now got the answer for the first one. but i still don't know how to approach the problem even if it's restated that way. and yes, I'm sure i wrote it as it is in the textbook.

I have some series related questions: 1) Find the limit of $\frac{(2n-1)!}{(2n+1)!}$ I know each term is less than one, but i don't know how to use this to get the limit 2) Find the limit of the sequence $\left(\sqrt{2},\,\sqrt{2\sqrt{2}},\,\sqrt{2\sqrt{2 \sqrt{2}}},\cdots\right)$ 3) $a_n =...

i got the answer to the following problem wrong: "there are four children in in the family. what is the probability that there are three girls, given that the youngest child is female?" my (updated) answer: the youngest is female, so three out of two children must be female. there are three...

A certain couple is equally likely to have either a boy or a girl. If the family has four children, let X denote the number of girls. Determine the probability distribution of X. (Hint: There are 16 possible equally likely outcomes. One is GBBB, meaning the first born is a girl and the next...

thanks, i can solve it now :)

how do i integrate (x^2 + 2x + 1)sqrt(4x^2 + 8x + 5)??

Re: trig integrate i still can't work it out. how do i integrate sec^3[x]*tan^2[x]??

how do i integrate the fifth power of a secant? i broke it up into powers of two and three but that didn't seem to work

i notice i have much problem solving questions regarding surface areas and volumes of rotation. it's not so much the setting up of the integration but i can't do the computing. can you guys suggest online practice problems to do integration required in these kinds of problems?? thanks :)

how do i integrate sin(pi*x)*sqrt(1 + pi*2*cos(pi*x)^2)? i reduced this to sqrt(u^2-u) but i don't know how to go from here

how do i integrate the function sqrt(1 + 1/2(y^1/2 - y^(-1/2))^2) from 0 to 1??

Re: two volume-related questions i think i now get #1but i don't know how your link relates to my question. is the solid in question in the thread a torus??