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Apr
18
answered Find the height of statue.
Apr
18
comment Deriving a formula for a confidence interval
I think you should have a plus sign in the numerator of your pooled variance normally. Consider looking at the Welch t test when variances are not assumed to be equal.
Apr
18
comment Deriving a formula for a confidence interval
What are you studying?
Apr
17
comment Easy proof of Black-Scholes option pricing formula
It's kind of intuitive don't you think?
Apr
17
revised Find distance between two poles.
edited body
Apr
17
answered Find distance between two poles.
Apr
17
comment Find distance between two poles.
How is tan(ACB) = AB/BC. The angle ACB is not even part of a right angle triangle given the way you have described the situation.
Apr
17
comment Is it valid to get a correlation between moving averages?
I think it is fine to use the moving average, as while each day data point will be used 10 times, each moving average data point only counts 1/10th of this, and effectively with a large data set the moving average should yield the same correlation as a day by day analysis. I say a large data set because the first 9 data points won't be counted a full 10 times, nor the last 9 data points, so provided you have much more than 18 moving average data points you should be ok.
Apr
17
comment How sample size affects confidence interval.
In this example, sigma is the population standard deviation, and thus is independent of sample size. So your answer is correct. Technically however your working should be 1.96sigma/sqrt(n) is the margin error, but the 1.96 cancels out anyway.
Apr
17
comment Simple interest problem
@Al.Ka, my belief is that the best way to teach is by direct instruction. If a student sees enough well worked examples, they will learn to emulate that over time.
Apr
17
comment Simple interest problem
@Larry, what about my answer, I answered first.
Apr
17
answered Simple interest problem
Apr
4
accepted For what k values are there more than one solution to the following equation?
Apr
4
comment When will one maximum turn into three maximums?
@ClaudeLeibovici, by distinct, I mean when there exists three maximum solutions to the equation y'(x) = 0, as opposed to x = 0 being the only such solution.
Apr
4
accepted How to solve this equation for x? $0 = (x+k)e^{-(x+k)^2}+(x-k)e^{-(x-k)^2}$
Apr
4
comment Using CLT to calculate probability question
What is the "right answer" ?
Apr
4
awarded  Custodian
Apr
4
reviewed Approve For what k values are there more than one solution to the following equation?
Apr
4
asked When will one maximum turn into three maximums?
Apr
4
revised For what k values are there more than one solution to the following equation?
added 475 characters in body