All Answers

+118725

Guest:
30 + (.0825 x 30) + (15% x 30) =

Jut put it straight into your calculator. 15% is 15/100

MelodyMar 1, 2014

+6252

well I'm glad I kept my responses brief.

I have to admit I had didn't recognize either of those names.

(next time I'll do my Foster Brooks act!)

RomMar 1, 2014

+6252

it would help greatly if you were able to tell us what the probability distribution of X is.

RomMar 1, 2014

+33666

George MacDonald was a Scottish author, poet, and Christian minister. He was a pioneering figure in the field of fantasy literature and the mentor of fellow writer Lewis Carroll.(whose real name was C.L.Dodgson).

AlanMar 1, 2014

+33666

DavisDude:
In rectangle ABCD, diagonal AC is drawn. If CD=8 and AC=13, find m < ACD

if you sketch the rectangle you will see that cos(ACD) = 8/13, so you should be able to determine angle ACD from this.

AlanMar 1, 2014

+33666

Der:
could you please solve 2 cos (5x + 10) = 1 For 0< x < 360

You can see from below that there are several solutions that lie within the range 0<x<360

angles.PNG

AlanMar 1, 2014

Never mind I figured out how to work it.

Thanks,
John Brown

GuestMar 1, 2014

+893

cos(5x+100) = ? ....... work it out,
5x+10 = ? ................. work it out,
5x = ? ....................... work it out,
x = ? ......................... work it out.

BertieMar 1, 2014

Help please

GuestMar 1, 2014

+135

lexiie96:
the painful wrist condition called carpal turned syndrome can be treatedwith surgery or less invasive wrist splints. in september 2002 time magazine reported a study of 176 patients. among half that had surgery, 80% showed improvement after three months, but only 54% of those who used the wrist splints improved. a) what's the standard error of the differences in the two proprtions? b) construct a 95% confidence interval for this diffence. c) state an appriopricat conclusion.

Hey lexiie96!

You can find the formulas for instance on:
https://en.wikipedia.org/wiki/Statistical_hypothesis_testing

In particular, the mean proportion p is:

p = (x1 + x2) / (n1 + n2)

where x1 is the number of people improved after surgery, x2 is the number of people improved with wrist splints, n1 is the number of people in the surgery group, and n2 is the number of people in the wrist splint group.

The standard error SE is:

SE = sqrt(p (1 - p) (1/n1 + 1/n2))

Perhaps you can use those formulas to find your answers?

You can get more and quicker help for this and similar questions indeed for instance on MHB.
If you register with this link, you'll give me a brownie point:
http://mathhelpboards.com/forum.php?referrerid=178
I do not know which referrerid Melody has though.

I like SerenaMar 1, 2014

That is the funnest thing I ever read on a math site. It is worth $1002

It is classic. A math fight of droll and witty repartee. Too bad it didn't continue longer

Most math jokes and humor are not very funny. But this is great!

It is way better than the 10 cents Weapons of Math Instruction. Even 10 cents is over priced. It might be worth 1 cent.

Mr. Rom you should have said are you for real or imaginary?

Then Mr. MacDonald could find something complex from the z-dimension of space to retort with.

Maybe Mr. Dodgson could comeback with a interdimentional retort of his own. Like where I come from middle schoolers are taught this only if they missed the concepts in grade school.

So how about it? Could you develop an algorithm to keep it going for awhile?

I haven't laughed so hard since the Dean Martin Roasts.

Thank for the laughs

GuestMar 1, 2014

+118725

Stu:
This is a quadratic equation right?
Can you show me the steps to solve.

y = 2cos(x) + x² + 2x - 7

Hi Stu,
Where did you dig this up from?
No it is not a quadratic equation. It is not even a quadratic function.
It would be a quadratic function if it did not have the 2cos(x) in it.
As for solving it, there is nothing to solve. It is just y =.
to solve it it would have to be some number equals (without the y)

I graphed this function for you to show you what it would look like.
But that is it from me on this one.
140301 Stu.JPG

MelodyMar 1, 2014

#53

+118725

+14

Hello everyone,
It was a very quiet Friday/Saturday. This is completely usual.
There were some great answers posted by 19fieldsm, Alan, Lexiie96 and samgelinas.
19firldsm (meggy) and lexiie96 joined us today. Welcome to Web2.0calc forum. We hope you like it here.
Each day about a half dozen member join up. I usually only mention the ones that make posts, but you are all very welcome here.
I know there are members who are here regularly and never or rarely make posts. I get the very occasional post or private letter where people tell me how much they like to watch and learn from other people's posts. Some of these people, although I am sure not all, struggle with English. If you are one of these people, I think that is great.
Enjoy your weekend or what is left of it.
Melody.

MelodyMar 1, 2014

+118725

bump

MelodyMar 1, 2014

+118725

*
PRINTABLE PUZZLES - WEB SITE.

This site has many different printable puzzles. They also come in many different difficulty levels.
I really like the Kakuro puzzles but there are many good ones.

http://krazydad.com/ Highlight the address, right click then click on goto
This is a picture of the introduction page, You will have to go to the web page to get into the puzzles and print them out.

140228 Krazydad Printable Puzzles, Mazes and more.JPG

MelodyMar 1, 2014

+118725

Here is one someone can play with if they want to . I dug it out of the archives.

MelodyMar 1, 2014

+33666

judie:
/x/-2

The absolute value of -2 is just 2. In general, if you want to enter the absolute value of a number in a calculator on which there is no absolute value button, you could square it and then take the square root again!

AlanMar 1, 2014

+118725

Yes maybe. thanks Alan.

MelodyMar 1, 2014

+33666

Melody:
mmann:
Nakisa spent $ 328 on a total of 22 CD's and a DVDs if CD's cost $16 each, how many CD's did Nakisa
buy?

Hi mmann,

I don't think that the question makes sense.

It says in the question that Nakisa bought 22CDs

22*$16 = $352 which is more than Nakisa spent.

See, it does not make sense.

I think this might mean
n _CD + n _DVD = 22
16n _CD + c _DVDn _DVD = 328

where n is number and c is cost. However, we still need to know the cost of a DVD to answer the qustion.

AlanMar 1, 2014

+118725

judie:
/x/-2

I am not sure what you want to do.
I've never entered absolute signs on any calculator except when I am graphing a function.

MelodyMar 1, 2014

+118725

mmann:
Nakisa spent $ 328 on a total of 22 CD's and a DVDs if CD's cost $16 each, how many CD's did Nakisa
buy?

Hi mmann,

I don't think that the question makes sense.

It says in the question that Nakisa bought 22CDs

22*$16 = $352 which is more than Nakisa spent.

See, it does not make sense.

MelodyMar 1, 2014

+118725

Matthew123456:
francois spent 20% of his savings on a bike and 15% of the remainder on a books. What percentage of his savings did he have left?

Let x be his savings.

0.2x was spent on a bike leaving him with 0.8x

0.15 of 0.8x = 0.12x was spent in books

Amount left = 0.8x - 0.12x = 0.68x

So he had 68% left.

MelodyMar 1, 2014

+118725

FELI0720:
To get 6500 after 8 years at 10% compound quarterly

what is the question?
Do you want to know how much to put in the account and then just leave it there to grow
OR
do you want to know how much to put into the account each quarter starting with 0
OR
do you want to know something else?

MelodyMar 1, 2014

+118725

A boat heads directly across a river at 8 mi/h. The river flows downstream at 10 mi/h. What is the resulting speed and direction of the boat

Hi problem solver,
If you are the problem solver, how come i am solving your problems ?

140301 river currents Trig.JPG

MelodyMar 1, 2014

+118725

Harbour:
The proportion of graduating students in a certain discipline who wait for three months before getting employed for the first time is 41%. If 9 fresh graduates from the discipline are taken at random, what is the probability that

(a) exactly four (b) between 2 and 5 inclusive (c) at least 3 wait for three months before getting jobs.

This is a combination question.
P(more than 3 months to get a job) = 0.41 p=0.41
P(getting a job before 3 months ) = 0.59 q = 0.59

P(exactly 4 out of 9 take longer) = 9C4 * 0.41 ⁴ * 0.59 ⁵

P(between 2 and 5 inclusive wait longer) = [9C2 * 0.41 ² * 0.59 ⁷] + [9C3 * 0.41 ³ * 0.59 ⁶] + [9C4 * 0.41 ⁴ * 0.59 ⁵] + [9C5 * 0.41 ⁵ * 0.59 ⁴]

P(at least 3 wait 3 months) = P( 3,4,5,6,7,8 or 9 wait 3 months) = 1 - P(only 0,1 or 2 people wait 3 months)
= 1 - [ 9C0 * 0.41 ⁰ * 0.59 ⁹ + 9C1 * 0.41 ¹ * 0.59 ⁸ + 9C2 * 0.41 ² * 0.59 ⁷ ]
= 1 - [ 0.59 ⁹ + 9 * 0.41 * 0.59 ⁸ + 9C3 * 0.41 ³ * 0.59 ⁶ ]

MelodyMar 1, 2014

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