Melody

921 Questions
34315 Answers

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Mathigon website

I just discovered a site called mathigon

https://mathigon.org/dashboard
lee mas ..

Melody 2 abr 2022

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Reporting problems.

There are a number of people having problems at the moment.
If you lodge an error can you please give all relevant information that you can think of.
Where you are in the world - the city or the country - is often very important information. lee mas ..

Melody 16 mar 2022

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How to make an empty rectangle in Latex

I just worked out how to make an empty box of various horizonal size easily in LaTex.
This is not a recommended method, but other methods that I have tried here have not worked.
This coding is really simple. Just put letters inside lee mas ..

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Melody 15 mar 2022

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858

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HAPPY ANNIVERSARY CHRIS! (CPhill)

I just realized that you became a member here exactly 8 years ago today!

It has been great to have you here all that time

Fuera tema

Melody 13 mar 2022

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WELCOME BACK CPHILL !

Melody 11 feb 2022

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Very interesting question. No high level maths required.

This question was posted a couple of days ago.
https://web2.0calc.com/questions/geometry_73561

I think it is really interesting. It looks much more difficult than it really needs to be. lee mas ..

Melody 1 feb 2022

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Members have a better experience. Their questions get more attention.

Almost everyone is posting as a guest.
If you post as a member your questions will have a far greater chance of a timely and helpful response.
If you are a genuine learner and interact with us, you will become known and answerers will do lee mas ..

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Melody 9 ene 2022

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HAPPY BIRTHDAY CHRIS!

Melody 20 dic 2021

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Some guidelines for question askers.

Please note:
1) Ask only one question per post.
2) When asking a question talk about what you have tried for yourself. Then people will take you more seriously and will be more able and willing to help.
3) If you get an answer lee mas ..

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Melody 4 nov 2021

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Remeniscing - a little historical humour.

I just found this old post that some of you, who have been around for a while, might find amusing.

https://web2.0calc.com/questions/look-at-the-new-leader-board

Fuera tema

Melody 29 oct 2021

+118690

0

H ey everyone well I'm in a cocky good mood today and I think I can answer every question *THINK* NOT *KNOW* So try me ? I'll do my best thanks ! Just ask away on my forum please

Hi Melissa,
I just went back and looked and this was your cousins last post. It is not even a question and it had a lot of respones so I don't know what you or her are complaining about!
Melody.

Melody7 dic 2013

+118690

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The value of an endowment policy increases at the rate of 5% per annum.
The initial value is £7000.
(a) Write down a recurrence relation for the policy’s value after n years.
(b) Calculate the value of the policy after 4 years.

Hi Snowwhite,
Initial value = 7000

After 1 year = 7000 + 5% of 7000 => 7000 + 0.05*7000 => 7000 * (1+0.05) => 7000 * 1.05

After 2 years = (7000 * 1.05) * 1.05 => 7000 * 1.05 * 1.05 => 7000 * 1.05 ²

after 3 years = (7000 * 1.05 ² * 1.05 => 7000 * 1.05 ³

Can you see the pattern?
You can answer your own questions now.

Melody7 dic 2013

+118690

0

Hello Melissa,
I am sorry that your cousin is not getting replies to her posts. I reply to a great many posts and I can remember seeing her name.
I looked up the members section because I wanted to find her posts and then I could see for myself that what you say is correct. I cannot find her under members.
Do you know if she just puts in her posts as a visitor? It would be better if she signed up. It's less hastle in the long run.
Without seeing her posts I cannot 'see' why she feels ignored. Not everyone can answer every question of course. They have to have some idea of how to do it first.
I will look out for her name and will try to make extra sure that she is looked after. She is lucky to have a little cousin who looks out for her.
Melody.

Melody7 dic 2013

+118690

0

How do you solve 264 yd/s=___mi/h?
Please explain thoroughly, and explain it easily enough for a 5th grader to understand.

I will try!

264 yards / 1 second

You need to change 264 yards into miles
There are 1760 yards in a mile
with conversions you always have to multiply or divide.
A mile is much bigger than a yard so there will be less of them and the answer will be smaller.
Since the answer has to be smaller, it must be divide.
so
264 yards must be 264 divided by 1760 miles = 0.15 miles (from a calculator)

Now you need to change 1 second into hours. (It will just be a little bit of an hour)
There are 60 seconds in a minute and 60 minutes in an hour so
there are 60 times 60 = 3600 seconds in an hour.
so
1 second = 1 divided by 3600 hours = a very tiny number. Since I am explaining to a 5th grader I will just leave it the way it is at the moment.
so
264 yards/1second = 0.15miles/(1 divided by 3600)hours => 0.15 / (1 divided by 3600) miles/hour => 540 miles/hour
I just did this on the calculator, put it in exactly as I wrote it. Don't forget the brackets. The fraction line after 0.15 can be put in as a divide sign.

A fraction bar and a divide sign are really the same thing. For example, 1 divided by 2 = 1/2

I hope that helps.

Melody6 dic 2013

+118690

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Hello all,
It occurs to me that perhaps I should also introduce myself.
I have a Bachelor of Science (in mathematics) and a Diploma of Education in secondary mathematics. My mathematics results were very good. My teacher training results were excellent.
I have spent many years teaching in seconday schools and I also taught for a number of years in a University College.
I have also tutored a great many students on an individual basis and have had consistently excellent results.

I 'discovered' this forum on 28th September and became a member immediately.
At that time almost all all post were going unanswered and the level of the questions tended to be very low.
I took it upon myself to see that all mathematics questions were answered. (there would be very few exceptions anyway)
Now, the quality of the questions has improved markedly and the forum is just starting to attract some really enthusiastic budding mathematicians.
Now I actually try not to answer all the questions. Although I probably answer more than I should. I believe that it is very important that the forum users are given the opportunity and encouragement to offer solutions and other input.
I have a passion for mathematics and an even greater passion for nuturing mathematical learning and mathematical appreciation in others.
I hope the other forum users believe that I have had a positive impact. If anyone has had questions I don't think that they have been afraid to ask. That is what I, and others, are here for.

In the coming months I hope the forum users will start to develop a more interactive approach. This has been slow in coming but it is just starting to happen now.
Melody.

Melody6 dic 2013

+118690

0

Hi,
This is a video clip that I think you may be interested in.
It is how to solve an inequality and it is quite good.
It starts at a very early point but maybe this will be good for you.

The clip tells you that the only time an inequality is handled differently from an equality is when you multiply or divide by a negative number (you have to turn the sign around)
This true BUT
you also have to turn the sign around if you swap sides
for example
say you get near the end of solving an inequality and this is what you have
12 <= x
then the answer is
x >= 12

Other than this omission, the clip is very good.

http://www.youtube.com/watch?v=OKlRsTV43oY

Melody6 dic 2013

+118690

0

0.00015241579 in fraction form

Well,
0.23 = 23/100 2digits after the point so 100 on the bottom
0.0023 = 23/10000 4digits after the point so 10000 on the bottom
0.00031705 = 31705/100000000 8digits after the point so 100000000 on the bottom

do you see the pattern?
Now you can answer your own question I think.

Melody6 dic 2013

+118690

0

There is a 20% probability that a person inoculated with a particular vaccine will get the disease anyway. A county health office inoculates 83 people. What is the probability that exactly 10 of them will get the disease at some point in their lives?

This is a binomial probability question.
The probability that any inoculated person will get sick is 0.2
The probability that any inoculated person will not get sick is 1-0.2 = 0.8
The probability that the first 10 people get sick and the next 73 people do not is 0.2 ¹⁰ * 0.8 ⁷³

Trouble is, it might not be the first 10 people that get sick, it could be some other combination of 10 people that get sick, so a formula is needed to work out how many possible ways 10 people can be chosen from a total of 83 people. That formula is ⁸³C ₁₀

so the answer will be
⁸³C ₁₀ * 0.2 ¹⁰ * 0.8 ⁷³

This can be done on your calculator.

Melody6 dic 2013

+118690

0

This is a very difficult question Rosey, I am wondering why your brother didn't ask it for himself.
I am thinking that he is just curious and that it isn't really a school question.
You have to use calculus to answer this question.
I will run through the working for you and your brother.
First i will assume that the car is travelling horizontally when it comes off the top of the cliff.
So it's vertical velocity (speed) is 0
It's horizontal velocity is 10 miles per hour = 44/3 feet/second

Now there are 5280 feet in a mile
Gravity will make the car accelerate as it falls
Gravity = 32.176 feet/second ²

So what you have to do is work out how long it will take the car to fall to the water.
After doing lots of calculations I got 1.5768 seconds ( approximately)
Now, how far will the car travel horizontally in this amoount of time.
44/3 feet/second * 1.5768 = 23 feet approximately.

If your brother has done some calculus and wants more help with the mathematics then he or you can post again and I will try to help more.
----------------------------------------------------------------------------------------------
Translation.
Espero que esta traducción de Bing tiene sentido.

Esta es una pregunta muy difícil Rosey, me pregunto por qué tu hermano no pedirlo mismo.
Estoy pensando que es sólo por curiosidad y que no es realmente una cuestión de escuela.
Tienes que usar cálculo para responder a esta pregunta.
Correré a través del trabajo para ti y para tu hermano.
Primero voy a suponer que el auto está viajando horizontalmente cuando se trata de la parte superior del acantilado.
Así es vertical velocity (velocidad) es 0
Su velocidad horizontal es 10 millas por hora = 44/3 pies/segundo

Ahora hay 5280 pies en una milla
Gravedad hará que el coche acelera como cataratas
Gravedad = 32,176 pies/segundo [sup] 2 [primera]

Así que lo que tienes que hacer es resolver Cuánto tiempo tardará el coche al caer al agua.
Después de hacer un montón de cálculos tengo 1,5768 segundos (aproximadamente)
Ahora, qué tan lejos el coche viajará horizontalmente en este amoount del tiempo.
44/3 pies / segundo * 1.5768 = 23 metros aproximadamente.

Si tu hermano ha hecho algunos cálculos y quiere más ayuda con las matemáticas entonces él o publique otra vez y voy a intentar ayudar más.

Melody6 dic 2013

+118690

0

I do agree with you Jimsablast.

I'd just like to look at it slightly differently.

First consider
y ³ * y ² = yyy * yy = yyyyy = y ⁵
or
y ³ * y ² = y ³⁺² = y ⁵
--------------------------------------------
(-5) ⁴ * 5 ^(-8)

= (-1) ⁴ * 5 ⁴ * 5 ^(-8) (Just as you said)

= +1 * 5 ^4+-8

= 5 ^-4

= 1 / 5 ⁴

Melody6 dic 2013