Recent content by kosovo dave

I believe so. My teacher is a nerd and it shows in her problem sets. The solution ended up being 1-1/(23 choose 11)

Since my sum is running from k=0, I think I should use the case $$\binom{n+k-1}{n}$$. If I used $$\binom{n-1}{k-1}$$ my sum would be running from k=-1.

Do I want to use the positive case or the non-negative case?

I'm not sure I follow. I think the only other distribution we've learned so far is the geometric distribution but that doesn't seem appropriate here?

Thank you for the quick response. Would a poisson distribution be an appropriate approximation if the number of attacks was much larger? Say, 120000 instead of 12?

Homework Statement 12 non-distinguishable attacks from President Snow land in Panem’s 12 districts in a particular week. Assume the attacks are located randomly, with each configuration of attacks equally likely. What is the probability that some district had more than 1 attack? Homework...

By "ends" do you mean of the full plate (x = -L and x = L) or the half-space (x=0 and x = L)? I should also clarify that the ends of the plate (x = +/- L) sag beneath the x-axis.

Homework Statement I'm trying to find the boundary conditions for the following problem: A plate with length 2L is placed on supports at x = L/2 and x = - L/2. The plate is deforming elastically under its own weight (maximum displacement bowing up at x = 0). Both ends of the plate are free...

augment the nonhomogeneous system with a solution from the homogeneous one?

I don't know why, but I'm still having a hard time with this :/ Could you give me another hint? Here's what I tried: Ax=c if c= (0,0,1,0,0,0,0,0,0,0) I think the system would be inconsistent because row 3 of the augmented matrix would be all 0's and then a nonzero to the right of the vertical...

This might belong in the HW section, but since it's specific to Linear Algebra I posted it here. Alright, so we have a homogeneous system of 8 equations in 10 variables (an 8 x 10 matrix, let's call it A). We have found two solutions that are not multiples of each other (lets call them a and...

Since I only have 2 variables, can't I throw away that row of 0's in the RREF matrix? I still think I'm missing something here. I don't quite see why a free variable makes the null space a line, plane, etc. Maybe I'm approaching what the null space is in the wrong way. I'm thinking about it as...

So a question on my linear algebra homework asks for the dimensions of Nul(A) and Col(A). Let A = \begin{pmatrix} -4 & -3\\ -1 &4\\ -3& -7 \end{pmatrix} I row reduced the above matrix to \begin{pmatrix} 1 & 0\\ 0 & 1\\ \end{pmatrix} Now, the T.A. for my section told us that to find the...

Thanks for the quick and thorough response @Mark44 ! In general though, it's probably just easier to "jam" the given column vectors v1, v2, v3 together into a matrix, right? Also, did you immediately notice that v1 = 2v2 - v3? Or was it plugging values in for c1, c2, c3 that allowed you to see...