Hi folks,
I'm no math or WolframAlpha expert, but I'm taking a probability class and encountered a problem where I have to solve for the standard deviation of a normal distribution. I boiled down the problem into: $$.9 = \int_{117}^{207} \frac{1}{x} \frac{1}{\sqrt{2\pi}} e^{-\frac{(\frac{y - 162}{x})^2}{2}} dy$$ solving for x.
I realize this is super computationally expensive and my TI-84 was making that known, so I plugged it into Wolfy:
.9 = integral(117,207) (1/x * 1/((2*pi)^(1/2)) * (e)^(-((y-162)/x)^2 / 2)dy)
"Wolfram|Alpha doesn't understand your query"
Which is strange because it understands a much simpler command:
.9 = integral(117,207) (x y dy)
I tried just about everything with syntax and could not get it to work, it seems to get stuck when there is (a term with an x) * e^(term with x and y)
My potato calculator eventually pulled through, but I wanted to know what the problem was.
Feedback appreciated, thanks,
Bryce Costawong