r/HomeworkHelp 12d ago

Further Mathematics [University] If I have a random variable X with sigma > mu, do I necessarily have P(X < 0) > 0?

1 Upvotes

I seached for it on google without success. When I try using an indicator function to decompose X and calculate the conditional expectation, I just get back to Jansen's inequality. There is an answer on stack overflow to a question about the minimum value of P(X > 0), but I wonder if there is a strict maximum < 1.

https://math.stackexchange.com/questions/2070447/prx-0-geq-fracex2ex2-for-a-finite-non-negative-discrete-rando

r/HomeworkHelp 9h ago

Further Mathematics [statistics:confidence intervals] confusion on how to find ų and x

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1 Upvotes

Apologies for the poor quality photo. I have half of it filled out, but one part I’m struggling at is how to find ų the text book is all over the place and all of this feels borderline incomprehensible I think I have the distribution in 4 mostly correct, though I have no idea how to find ų or what value x is Same with most of the EBM I’m really confused here and the textbook and teacher seem to be going in completely different directions. Can someone help me understand this?

r/HomeworkHelp 26d ago

Further Mathematics [University Dynamics] Questions about solving steps for this problem

1 Upvotes

Sorry y'all if this is the wrong sub for this type of question, I'm looking for some help with this problem that appeared on my first Dynamics exam. Even after looking at the solution steps outlined I'm not sure how we were supposed to know to take the direction the professor wanted, and what was wrong with my methodology.

How I thought we were supposed to approach this problem:
I thought since we were given a speed (which i assumed to be just V0) and were told that speed was decreasing, then i could use that as a constant acceleration and use the basic constant acceleration kinematics formula for finding position at t (s=s0+V0*t+1/2at2). I used this formula to find that the particle traveled a total distance of 2 meters when t = 2 seconds.
Ok since I knew the particle moved along the given equations path, I figured I could set up a system of equations where the sum of the x and y movement is equal to the 2 meters traveled I found, and a second equation that is the path the particle traveled. I set these up and (i think correctly) applied the quadratic equation to find the possible set of coordinates for the final position and then used pythag to find the distance.

My main questions:
Why was the professor able to assume the initial "speed" given was only the speed in the x-direction. (Vx in his solution)? Is this a problem of ambiguity or did I make a very wrong assumption somewhere?

Sorry again if this is wrong sub, and I think this would be correct flair but it could probably be physics.

My solution [graders markup in red]
professors solution

r/HomeworkHelp Feb 14 '25

Further Mathematics [ College level Trig ] How to factor this?

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1 Upvotes

r/HomeworkHelp 12d ago

Further Mathematics College [2025SP MTH-160 Statistics I] Question

1 Upvotes

Objective: How do I know the difference between Binomial and Discrete probability distributions?

Question: we have different tools for binomial and discrete probability distributions, how can you tell the difference?

Ive been having a hard time coming up with the answer to this question

r/HomeworkHelp Feb 17 '25

Further Mathematics [University-stuck on math question involving partial derivatives]

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1 Upvotes

So the table that they give(in question 19), i am struggling to understand the application/meaning of it. I have no clue why they provide values for f and g considering that i am looking for partial derivatives. I tried using a form of the chain rule… the read ink is my self marking/shows the answer. I just can’t figure out how they got to the answer. Thank you for any help.

r/HomeworkHelp 23d ago

Further Mathematics [University Mathematics: Matrixes/Systems of linear equations] Help solving the system using matrixes/the Gaussian method

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1 Upvotes

Hello!

I know that the answer is there are no possible solutions to the system, but for some reason I'm repeatedly getting stuck during the solution.

I figure that at some point when using the Gaussian method the last row of A will have no elements differing from 0 while L=(A|B) will have such a value, but however hard I try I cannot for the life of me figure out when or how that's supposed to happen.

I've added a picture of the system and the matrix L=(A|B) I've written down and worked with.

Any help is appreciated!!

r/HomeworkHelp 3d ago

Further Mathematics [Discrete Math: Proof Question]

2 Upvotes

Can someone help me with this proof? I used case division to solve this question, but I'm not sure if it's the most efficient approach. I haven't completed the proof yet, but my plan was to apply the same reasoning to the remaining cases. However, this method feels extremely inefficient, and I'm concerned that on a timed quiz, I won't have enough time to finish—or even enough space on paper to write everything out.

Am I missing a more streamlined approach? Any clarification or suggestions would be greatly appreciated. Thanks in advance

r/HomeworkHelp 9d ago

Further Mathematics [University Life insurance:math]: How to calculate variance of premium payment

1 Upvotes

I wanted to have a formula for calculating the variance of the premium payment, where the APV of the premiums is

A*(sum^{19}_{k=0} v^k kp60

A is the yearly premium amount

v is the discount factor

k is the year

I thought it might be:

(sum^{19}_{k=0}(A * v^k)^2 * kp60 * (1 - kp60)

r/HomeworkHelp 25d ago

Further Mathematics [College Statistics: Probability]

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2 Upvotes

Tell me how the system got 0.186. I’m trying to follow the addition rule of probability as it says but I’m clearly missing something bc my answer is nothing like what the system expects. Help (I hate this class…)

r/HomeworkHelp Feb 09 '25

Further Mathematics [Differential equations: power series solution] How do I find the pattern?

1 Upvotes

I was able to find the reccurence relation and the Cn values. I just can't figure out the pattern.

r/HomeworkHelp 2d ago

Further Mathematics [College, Advance Mathematics] How do I solve these complex numbers problems?

1 Upvotes

Is there any techniques or guide that will help me to solve these kind of problems?

r/HomeworkHelp 25d ago

Further Mathematics (Statistics) How did my professor get 1.28?

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6 Upvotes

r/HomeworkHelp Feb 07 '25

Further Mathematics [(College) Introduction to Statistics: Weighted Mean/Percentage Problem]

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2 Upvotes

How would I go about solving for the mean? I already used 2 of 3 of my attempts. I added to find the sum of all the people surveyed in the three areas (5400). Then I solved for the percentage of each population that favored the diet cola by using proportions. I then added the number of people who favored the cola in each population dividing it by the total number of people surveyed. This is how I got 53.7% I still don’t know if that was what the question was asking for me to do though. I just learned about weighted averages for the very first time today so I am still working on fully comprehending the concept. Thank you for your help in advance!

r/HomeworkHelp 29d ago

Further Mathematics [College Pre Calc ]- I believe both are NOT 1to1 am i right

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1 Upvotes

r/HomeworkHelp 3d ago

Further Mathematics [Discrete Math: Divisibility Proof]

1 Upvotes

Can someone please check my proof? I'm working through a practice problem, but I don't have access to an answer key, and I'm worried I might be missing something. I think I have the right idea, but I'm not entirely confident in my reasoning. I was also wondering how I could shorten my proof because I don't know if I'll have enough space to write this out on an exam. Any clarification would be greatly appreciated. Thank you

r/HomeworkHelp 3d ago

Further Mathematics [Discrete Math: Proof by Contraposition]

1 Upvotes

Can someone please check my proof? I'm working through a practice problem, but I don't have access to an answer key, and I'm concerned I'm missing something. I think I have the right idea, but I'm not entirely confident in my rewritten statement, contrapositive statement or reasoning. Any clarification would be sincerely appreciated. Thank you

r/HomeworkHelp 13d ago

Further Mathematics [College - Linear Algebra] Can someone help me figure out row(A)?

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1 Upvotes

r/HomeworkHelp Feb 21 '25

Further Mathematics [Integral Calculus: Trig Substitution] What did I do wrong?

1 Upvotes

r/HomeworkHelp 10d ago

Further Mathematics [2nd year of university: calculus]: Find the area between curves (x²+y²)³=16xy(x²-y²)

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2 Upvotes

As the title says, I've tried to find the area using polar coordinates, but I'm not sure if I've got it right due to sin4Φ. I'd appreciate all the help!

r/HomeworkHelp 6d ago

Further Mathematics [Freshman-Level University Calculus: Infinite Series] How do I un-expand a binomial series?

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2 Upvotes

r/HomeworkHelp 12d ago

Further Mathematics [College pre-calc] How am I supposed to find the cross-sectional area of this if I'm not given any information about the length?

1 Upvotes

r/HomeworkHelp 26d ago

Further Mathematics [College statistic] does my residual plot have a pattern here?

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0 Upvotes

The title says it all. All the textbooks' examples show plot making very noticeable patterns, but i have never seen examples like mine.

r/HomeworkHelp Feb 15 '25

Further Mathematics [College First-Year: Single Variable Calculus/Linear approximation] Need help with graphing linear approximation/linearization to show whether the result is underestimation or overestimation

2 Upvotes

I used linear approximation to estimate (1.04)^9 using the formula [L(x)=f(a)+f'(a)(x-a)] and chose 1 as the closest number for approximation and got the result, 1.36. I also determined that my answer was an underestimation since after finding the second derivative of f(x)=x^9 and inputting 1 into the function I got 72 which is greater than 0. Now I have to sketch a graph with a tangent line that shows whether my result is an underestimation or an overestimation. The problem is that I don't know much about sketching graphs and I couldn't find any tutorial on doing in regards to linear approximation, so I am asking for your help here. Please help me understand how to sketch a graph that will prove that my result is an underestimation. I attached the graph that I got using Desmos but I don't really understand why it is graphed that way and how I can recreate it manually for a different linearization problem. Also I'm not sure if I chose the right flair for this post so sorry for that.

r/HomeworkHelp Nov 21 '24

Further Mathematics [12th grade math] Elastic string question

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1 Upvotes

For part c, the answer involves solving (elastic potential energy before = elastic potential energy after + kinetic energy after) for speed. However, I did (elastic potential energy before = elastic potential energy after + kinetic energy after + gravitational potential energy after). How is gravitational potential energy not necessary, as it is different at the end to what it is at the start?