Wait, what? I don't think 5/(26*26) would be the right answer, since that implies there is a 5 in 26^2 chance that they get the answer right on the first try...
My teacher has since told me to assume the attempts are independent (dumb hacker, I guess) so I'm modeling this as a geometric...
Homework Statement
Consider a simple password scheme using only two lowercase letters. A hacker is given 5 chances to guess the pw before being detected. Computer probability hacker is successful.
Homework Equations
p = 1/(26*26)
The Attempt at a Solution
I'm assuming the...
Ok I understand it now. That clears up a lot, and explains the missing term I needed to make things all nice. (I would have another theta term in the numerator to cancel the one out in the denominator).
That helps alot, but if it wasn't for checking my work I would've been surely wrong. Any idea why my method didn't work; it's a trick my professor uses to solve problems with 'known' solutions.
Homework Statement
A density function used is:
f(y) = \frac{2y}{\theta}e^{\frac{-y^{2}}{\theta}} y > 0
using method of transformations find:
(a) pdf of U = Y^2
(b) E(Y) and V(Y)
Homework Equations
f(u) = f(h^-1(u))*|dh^-1/du|
h^-1(u) = sqrt(u)
The Attempt at a Solution
The...
Homework Statement
A box contains 5 keys, only one of which will open a lock. Keys are randomly selected and tried, one at a time, until the lock is opened (keys that do not work are discarded before another is tried). Let Y be the number of the trial on which the lock is opened. What is the...
Heres a try at the first one
m = (a+n)/2 is an integer only if m is even which => (a+n) must be even.
(a+n) is even if a & n are both even or both odd which covers a for both even and odd integers
Homework Statement
Determine whether f: ZxZ->Z is onto if
(a) f(m, n) = 2m-n
(b) f(m, n) = n^2 - m^2
(c) f(m, n) = m + n + 1
(d) f(m, n) = |m| - |n|
(e) f(m, n) = m^2 - 4Homework Equations
A function is onto if for every y in the codomain there is at least one X in the domain st f(x) = y
The...