Free Math Help ForumAsk your question to get free math help in algebra, geometry, trig, calculus and other subjects. We won't do your homework, but come prepared to explain where you need help and discuss your math questions with others.Fri, 26 Feb 2021 01:05:47 +0000Fri, 26 Feb 2021 01:05:47 +0000Free Math Help Forum
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Random sampling questionFri, 26 Feb 2021 00:16:08 +0000
https://www.freemathhelp.com/forum/threads/random-sampling-question.128409/
https://www.freemathhelp.com/forum/threads/random-sampling-question.128409/invalid@example.com (MysticMag)MysticMagokay guys this is the question:
A zoo has 80 cotton-top tamarins. Describe in detail how the random- number table given below could be used to select a sample of 5 of them, for a study of tail lengths.
8330 3992 1840 0330 1290 3237 9165 4815 0766 (5marks)
So im not really sure where to go with this one, i can't see it being any type of systematic so it must be simple random sampling, but the issue is, there are nine groups of...
Random sampling question]]>1Number Theory questionFri, 26 Feb 2021 00:08:24 +0000
https://www.freemathhelp.com/forum/threads/number-theory-question.128411/
https://www.freemathhelp.com/forum/threads/number-theory-question.128411/invalid@example.com (Jomo)JomoI tried everything I know about number theory ( a course which I never took before) but can not solve the problem below. Can someone please solve it for me or give a leading hint? Thanks!
Prove that there exist two distinct natural numbers m and n with m, n≤2049 such that 19^{m}−19^{n} is divisible by 2019.The truth of this claim does not depend on the exact values 19, 2019, and 2049. So, your solution should give an argument that is easy to adapt to other values for these...
Number Theory question]]>1Parametric Equations for a Rotating Object on an InclineFri, 26 Feb 2021 00:00:47 +0000
https://www.freemathhelp.com/forum/threads/parametric-equations-for-a-rotating-object-on-an-incline.128390/
https://www.freemathhelp.com/forum/threads/parametric-equations-for-a-rotating-object-on-an-incline.128390/invalid@example.com (Hello4749)Hello4749Hi, I started off by writing the parametric equations as if the rock was rolling on a flat surface.
What I got by drawing sin/cos graphs and basing my answers off example problems:
x = 1t + 5sin(2πt)
y = 10 - 5cos(2πt)
x is horizontal distance, y is vertical distance, t is in minutes
Are these close to correct or helpful in solving the problem? I'm mainly not sure how to account for the incline or angle of the hill. I know that it'll change the y equation a lot. Should I be doing something...
Parametric Equations for a Rotating Object on an Incline]]>4Looking for app for learning basic factsThu, 25 Feb 2021 23:31:29 +0000
https://www.freemathhelp.com/forum/threads/looking-for-app-for-learning-basic-facts.128404/
https://www.freemathhelp.com/forum/threads/looking-for-app-for-learning-basic-facts.128404/invalid@example.com (mrmac22448)mrmac22448Home schooled niece is bored with learning basic arithmetic facts. Any ideas?]]>3Surface Area (Again)Thu, 25 Feb 2021 23:13:50 +0000
https://www.freemathhelp.com/forum/threads/surface-area-again.128389/
https://www.freemathhelp.com/forum/threads/surface-area-again.128389/invalid@example.com (Amuziart)AmuziartHello everybody and thank you so much again for all your wonderful help! I am wondering if someone could please look over my work and tell me where I went wrong? First photo attached is the question I'm working on and the second photo is my work. My textbook says my answer should be "about 21.9m^2" however my total surface area only equals 20.4m, without even subtracting the overlap! Thank you very much]]>4Derivation of Viability Selection Difference EquationThu, 25 Feb 2021 22:59:10 +0000
https://www.freemathhelp.com/forum/threads/derivation-of-viability-selection-difference-equation.128410/
https://www.freemathhelp.com/forum/threads/derivation-of-viability-selection-difference-equation.128410/invalid@example.com (jp5125)jp5125Hi all,
This probably isn't a super tough question for any of you to answer, but I'm stumped on this and could use some help. I am an evolutionary biologist and my background in mathematics is solid but by no means phenomenal. I am delving deeper into mathematical modeling of evolutionary phenomenon and am working through Richard Mcelreath and Robert Boyd's book "Mathematical Models of Social Evolution". I have taken up to pre-calculus and loads of advanced multivariate statistics courses...
Derivation of Viability Selection Difference Equation]]>0Finding numbers for two sidesThu, 25 Feb 2021 22:52:41 +0000
https://www.freemathhelp.com/forum/threads/finding-numbers-for-two-sides.128407/
https://www.freemathhelp.com/forum/threads/finding-numbers-for-two-sides.128407/invalid@example.com (Diannev)DiannevI need help finding either one of those numbers in inches. Please help
Thank you!]]>1PoissonThu, 25 Feb 2021 22:11:07 +0000
https://www.freemathhelp.com/forum/threads/poisson.128408/
https://www.freemathhelp.com/forum/threads/poisson.128408/invalid@example.com (Topher_1202)Topher_1202The number of black bear sighting on a route in Charlevoix follows a Poisson process with a mean of 5.6 per year. a) What is the mean time between sighting? b) What is the probability that there are no sighting within 5 month? c) What is the probability that the time until the first sighting exceeds 3 month?]]>1Slope Intercept EquationThu, 25 Feb 2021 22:08:25 +0000
https://www.freemathhelp.com/forum/threads/slope-intercept-equation.128400/
https://www.freemathhelp.com/forum/threads/slope-intercept-equation.128400/invalid@example.com (mhester88)mhester88My teacher is struggling this semester with her own person problems and hasn't been around much to help us. I got this question wrong because I didn't write out the slope intercept form equation. If I understand correctly, the slope intercept equation is y=mx+b. Which in this case would mean y=-5/4x-9/4.
Is anyone able to check my understanding of how to find the slope intercept equation for this problem?
]]>4Geography - sort ofThu, 25 Feb 2021 21:18:02 +0000
https://www.freemathhelp.com/forum/threads/geography-sort-of.128355/
https://www.freemathhelp.com/forum/threads/geography-sort-of.128355/invalid@example.com (JohnRedman)JohnRedmanWhat is the Lat and Lon of a point 716.03 feet away in a direction of 50 degrees, 9 minutes and 10 seconds from N 43 degrees, 32.305 minutes Lat and W 71 degrees 55.903 minutes Lon?
What is the Lat and Lon of a point 1175.19 feet away in a direction of 44 degrees, 30 minutes and 20 seconds from N 43 degrees, 32.295 minutes Lat and W 71 degrees 56.024 minutes Lon?
Location is in Grafton, NH at 350 Dean Rd. I can only locate the two pins that I give locations for and I can't afford a new...
Geography - sort of]]>3Diagonal of a square from 4 pointsThu, 25 Feb 2021 20:03:43 +0000
https://www.freemathhelp.com/forum/threads/diagonal-of-a-square-from-4-points.128401/
https://www.freemathhelp.com/forum/threads/diagonal-of-a-square-from-4-points.128401/invalid@example.com (mhester88)mhester88I'm very lost on this word problem and have no idea what to do here. Is there anyone who understands this and may be able to help?
A diagonal of a square connects the points (-4,3) and (2,-3). Find the area and the perimeter of the square.
]]>5Geometry HW problemThu, 25 Feb 2021 19:58:34 +0000
https://www.freemathhelp.com/forum/threads/geometry-hw-problem.128402/
https://www.freemathhelp.com/forum/threads/geometry-hw-problem.128402/invalid@example.com (OPJT24)OPJT24
I've been trying to do this problem for my hw and I can't solve it. I tried making everything a iso triangle and filling the sides like that. How would you solve this problem?]]>3Simple Maths question?Thu, 25 Feb 2021 19:48:57 +0000
https://www.freemathhelp.com/forum/threads/simple-maths-question.128352/
https://www.freemathhelp.com/forum/threads/simple-maths-question.128352/invalid@example.com (sadcrimsonrhino)sadcrimsonrhinoHi
My first post so apologies if this is in the wrong place etc.
My son was set the following question as part of his maths work, and whilst I think the intention may simply be to brute force a solution, I was hoping to identify a more elegant way to solve this to walk through with my son and hoped someone here may be able to help.
Question:
S.NOW+
R.AIN
________
SL.EET
Where each different letter is unique.
We have worked out the first part, and deduced that S must be 1 and...
Simple Maths question?]]>3Need help ASAP with finding a formula for irregular "antiprism"Thu, 25 Feb 2021 19:41:20 +0000
https://www.freemathhelp.com/forum/threads/need-help-asap-with-finding-a-formula-for-irregular-antiprism.128396/
https://www.freemathhelp.com/forum/threads/need-help-asap-with-finding-a-formula-for-irregular-antiprism.128396/invalid@example.com (thestruggle02)thestruggle02Hi guys, I need help with finding a suitable formula that involves the VERTICAL HEIGHT (I mean the height from the centre of the pentagonal base straight up until it reaches the centre of the top pentagonal roof, just to be clear) of the antiprism as well as the length of the SIDES that make up the pentagonal base.
Is there any formula for this shape that I'm describing? I need help urgently as my assignment is due very soon.
someone suggested using...
Need help ASAP with finding a formula for irregular "antiprism"]]>4linear equation general strategyThu, 25 Feb 2021 19:19:15 +0000
https://www.freemathhelp.com/forum/threads/linear-equation-general-strategy.128406/
https://www.freemathhelp.com/forum/threads/linear-equation-general-strategy.128406/invalid@example.com (bobisaka)bobisaka5(a-3)+5=-10
5a-3+5=-10
5a+2=-10
5a+2-2=-10-2
5a=-12
5a/5=-12/5
a = 0
How and why is the answer zero?]]>2Annual Percentage RateThu, 25 Feb 2021 19:12:19 +0000
https://www.freemathhelp.com/forum/threads/annual-percentage-rate.128403/
https://www.freemathhelp.com/forum/threads/annual-percentage-rate.128403/invalid@example.com (Explain this!)Explain this!The cash price for an air condition is $150.00. The installment price is $170.10, payable in 18 equal monthly payments. What annual percentage rate is paid by the installment purchaser?
The amount financed per $100.00 is $20.10 divided by $150.00 multiplied by $100.00. The amount is $13.40. This amount is needed to determine the finance charge.
The answer is 16.25%, This percentage is found by using an APR table. My question is as follows:
How can the APR of 16.25% be determined by using...
Annual Percentage Rate]]>4Can somebody please help me answer this question? Thank youThu, 25 Feb 2021 17:13:29 +0000
https://www.freemathhelp.com/forum/threads/can-somebody-please-help-me-answer-this-question-thank-you.128304/
https://www.freemathhelp.com/forum/threads/can-somebody-please-help-me-answer-this-question-thank-you.128304/invalid@example.com (pleasehelpmewithmaths)pleasehelpmewithmathsTwo blended fruit juices are made from mixing pure juices in the following ratios:
Morning Delight: 3:1:5 for juices A, B and C respectively
Tropical Surprise: 2:3:3 for juices A, B and C respectively
120 litres of juice A is used to make Tropical Surprise. How many litres of Morning Delight could the same amount of juice A make?
]]>6Forming a Differential equation for a lake pollution modelThu, 25 Feb 2021 16:45:20 +0000
https://www.freemathhelp.com/forum/threads/forming-a-differential-equation-for-a-lake-pollution-model.128405/
https://www.freemathhelp.com/forum/threads/forming-a-differential-equation-for-a-lake-pollution-model.128405/invalid@example.com (Nutty_Noodle)Nutty_NoodleThe volume of lake = 150*10^9 Litre
The flow rate in and out of the lake = 20*10^6 Liter/year
Concentration, C(t)=4+sin(2t) grams/Litre
Assumptions:
Pollution not created or destroyed in the lake
Lake is well mixed
Form a differential equation describing this contamination flow and determine the amount Q(t) of toxic chemicals in the lake at time t
so yeah I am lost as to where to even start, I have researched other models but they all solve for C(t) so any and all help is welcomed, links...
Forming a Differential equation for a lake pollution model]]>0Irreducible Quadratic EquationsThu, 25 Feb 2021 15:42:35 +0000
https://www.freemathhelp.com/forum/threads/irreducible-quadratic-equations.128398/
https://www.freemathhelp.com/forum/threads/irreducible-quadratic-equations.128398/invalid@example.com (CharlieDoggers)CharlieDoggersHey guys
So this is my first time going through quadratic equations, so it's a bit rocky atm.
Right now I'm struggling to understand irreducible quadratic equations. For example 20 (found at the bottom of this post), my understanding is that the bracketed values are as a result of negating the squared symbol from x2 through finding the square root of x2, which results in the formula being x + 5x + 6 (which I hope is the case?). Where I encounter problems is understanding how factoring the...
Irreducible Quadratic Equations]]>4Calculus: This is all the info I have, I am not sure how to go about this problem.Thu, 25 Feb 2021 15:17:21 +0000
https://www.freemathhelp.com/forum/threads/calculus-this-is-all-the-info-i-have-i-am-not-sure-how-to-go-about-this-problem.128395/
https://www.freemathhelp.com/forum/threads/calculus-this-is-all-the-info-i-have-i-am-not-sure-how-to-go-about-this-problem.128395/invalid@example.com (hharleyyqquinn)hharleyyqquinnIf h(x) = square root 5 + 4f(x), where f(3) = 5 and f '(3) = 4