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Hi Jack3.142 I'm an astronomer and wanted to comment a little on some of things you said: The tilt of the Earth's rotation axis with respect to its orbital plane (the ecliptic plane) is fairly constant. But the axis does change direction (with constant tilt, so that it sweeps out a cone every...

Hi ReaPERudite The additional advice I'd offer, as a hint, is that it might be useful to convert the construction times in to rates, because these are directly additive. In other words, you have some values that are in "hours per fence", but it might be useful to have quantities in "fences per...

Hi Gyasa, welcome to the forum We need a lot more information than this to help answer the question. Is the steel cable attached to some mass? How big of a mass? Is the mass suspended vertically, or moving along the ground? Is a constant force being applied, or a varying one? Also, you need to...

Welcome to the forum Devi, As per forum guidelines (and just because it makes sense), please show us your work. What have you tried so far? How did you end up with 13/16? We can't help you if we can't see where you're going wrong. The pieces being arranged randomly implies that all...

At present, I'm unsure what that online calculator is doing ... does anyone else know? I could try to reverse engineer it later this week based on the example that's given. But I think I've answered the question of the original post. Summarizing what I said above: Can you use a chi-squared...

Yes, I understand what you are trying to do: in the portion of my post that you quoted above, I was re-iterating the problem. The question is: did you read any of the rest of my post? What did you assume for the variance? You can't solve the problem without that piece of information. You're...

Here's my take on this. The question doesn't seem completely well-posed, so I'll try to fill in some gaps. Let F = 0.52 (or whatever) be the proportion of the entire population that is female. You have a random variable f, which is the proportion of a particular 100-person sample of people that...

It looks like what you did was compute 0.95, which seems to make sense to me. After the first iteration you have a 90% water solution. In the second iteration, 90% of what you have is the 90% water solution, and 10% is pure alcohol. So that's 90% of 90%. Etc.

I'm not a moderator, but I imagine that it's fine to 1) Encourage politeness and make posters realize that people are giving generously of their free time to help them 2) Supply information about forum tools that would help posters make their queries more readable 3) Enforce established forum...

I am having a lot of trouble understanding exactly what the distinction is in your head between "holiday day" and "holiday entitlement". (That's "vacation day" for the Americans in the audience). Some points: - Yes, of course if you use up one holiday day, then you have one day fewer left to...

Hi martha, The "vector space" you are dealing with is now a space of all possible continuous functions defined on some interval, and the inner product of two functions in this space is defined as an integral over that interval, rather than just being a simple multiplication...

But also, the values in your third column are nowhere near what you'd get if you just plugged mu, sigma, and x (from the leftmost column) into the equation you posted. So now I have no idea what you actually did. Did you use software to compute a best fit to the data? If so, was the amplitude...

Hi, The pre-factor of 1/\sqrt{ 2\pi\sigma^2} on the equation you used is in order to normalize the Gaussian function so that its integral (over all x) is unity (one). This is because it's supposed to be a probability density function. I.e. the probability of getting some value should be 1...

Hmm, no responses so far. Well, a suggestion from a colleague of mine was that even if A and B have some non-zero covariance, the samples A^i and B^j act like independent random variables for i \neq j, because of the following reasoning. Suppose the covariance is positive. Then, if A happens to...

WHOAH. Back. Up. A. Step. I assume that you mean that your target return on investment is 6% slash 0.6. Not 6% divided by 0.6. If it was meant to be a slash, then we have a problem: 6% is NOT 0.6. 6% is 0.06. You are off by a factor of 10. You want to earn $5447 per year in property value...

In the first step, where you took the natural log of both sides, you assumed that ln(a+b) = ln(a)+ln(b). This is not true.

Hello everyone, This is not homework, it's a real problem I encountered in data analysis. I'll try to state the problem as clearly as possible, while removing extraneous information about the specific application. Statement of the Problem I have two random vectors A^i and B^j. Each of element...

Hi Erwin1998, welcome to the forum. It's been a while since I've had to think about bending moment (Introductory Mechanics, basically). But having researched it a little bit, it seems like there isn't enough information about the physics of the situation in order to solve the problem. For...

Yes No. Again, you need to understand what the Z-table is telling you. This tells you that the probability of being this far below the mean (or farther) is only 0.023. So that's something you know. You can use that information to determine what the probability of a Type II error is. But to do...

Yeah, but you need to be aware of what the "positive Z-table" is telling you. It's telling you the probability of being less than or equal to the Z-score you looked up. You want the probability of being greater than or equal to it. Hint: what is one minus the value you looked up?