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Apr
9
revised Find the probability that you have three of a kind after you pick 5 cards from a regular 52-card deck.
added 583 characters in body
Apr
9
answered Find the probability that you have three of a kind after you pick 5 cards from a regular 52-card deck.
Apr
9
awarded  Nice Answer
Apr
9
revised Conditional probability Maths question
added 488 characters in body
Apr
9
answered Conditional probability Maths question
Apr
9
answered Solids of revolution question
Apr
8
answered expected distance
Apr
8
comment How many zip codes are there with exactly one odd number?
One odd: The location of the odd can be chosen in $\binom{5}{1}$ ways. For each of these ways, the oddball can be chosen in $5$ ways. And now the rest of the slots can be filled with evens in $5^4$ ways. Two odd: Locations can be chosen in $\binom{5}{2}$ ways. The two locations can be filled with odds in $5^2$ ways. And the rest can be filled with evens in $5^3$ ways.
Apr
8
awarded  Enlightened
Apr
8
awarded  Nice Answer
Apr
8
awarded  Nice Answer
Apr
8
comment Improper integrals in curve length
For the first, simplify the integrand to $\frac{\sqrt{2}}{\sqrt{2-x^2}}$. Then make substitution $x=t\sqrt{2}$ and recognize the answer, or let $x=\sqrt{2}\sin\theta$.
Apr
8
comment How to find maximum/minimum of $y=\frac{x(x^2-x+2)}{x^2-9}$?
There is no (absolute) max or min.
Apr
8
comment Determine whether this series converges
The $2n-1$ at the bottom is I think not correct. (The $(2n-1)!$ is fine.)
Apr
8
revised Indeterminate limit that is supposed to be solved with De L'Hospital's rule
small typo fixes
Apr
8
comment Why is the Taylor expansion of $\cos$ decreasing?
Alternating series, as I mentioned, work nicely if $t\le 1$, but then stop working. However, the result is true for all positive 9and negative) $t$, so I thought I would prove it in general.
Apr
8
answered Probability using Chebyshev equation
Apr
8
answered Irreducible Polynomials over $\mathbb{R}$ or $\mathbb{Q}$
Apr
8
comment what is the Convergence radius and what happen at the edges?
Hint: Use the Root Test.
Apr
8
answered Why is the Taylor expansion of $\cos$ decreasing?