 Ask Remember Me?

# Search:

Type: Posts; User: galactus

1. ## Question: Use the given data to find the minimum sample size required to estimate the populatio

by galactus
2
Views
5,967

### Use the formula. It's just 'plug and chug'. ...

Use the formula. It's just 'plug and chug'.

n=p(1-p)\left(\frac{z}{E}\right)^{2}

If p is unknown, assume p=0.5

In this case, E=.015, \;\ z=1.645, \;\ p=.5

Round up to the nearest whole...
2. ## Question: Linear Programming

by galactus
2
Views
1,735

### Hi Unknown. Long time. :) Linear programming...

Hi Unknown. Long time. :)

Linear programming does not require calculus.

If one graphs the lines generated from the inequalities, one looks at the vertices of their intersections.

Basic...
3. ## Question: Find the tangent plane eq.

by galactus
1
Views
449

### You have a typo in your problem. What is 5x-2y...

You have a typo in your problem.

What is 5x-2y 1/2z?

+? -?

Are you sure that is not z=x^{2}+e^{y}?

Please make sure the problem is typed exactly as presented.
4. ## Question: Work problems with solutions and answers?

by galactus
3
Views
1,472

### This is a system of two equations with two...

This is a system of two equations with two unknowns.

Let m=number of memo pads and let p=number of pens.

They must make \$8400:

8m+5p=8400

They want to sell 120 items:
5. ## Question: What's the pattern in the sequences?

by galactus
1
Views
1,035

### This is one solution that works, though it is...

This is one solution that works, though it is rather abstract. These are the first 5 Euler Phi numbers of the first 5 composite numbers.

The Euler Phi function or Totient function, \phi(n), is...
6. ## Question: Limits [descriptive title]

by galactus
1
Views
380

### You are correct. It is indeed 0. It is not an...

You are correct. It is indeed 0.

It is not an indeterminate form. It is also continuous.

Thus, you can do that.
7. ## Question: Multipication Magic Square

by galactus
1
Views
500

### Do a search. Here is a site that may help: ...

Do a search. Here is a site that may help:

Behind the Magic Square Maker
8. ## Question: Combinations sum

by galactus
3
Views
515

### Look at the sum closely. N is a constant. Say...

Look at the sum closely. N is a constant.

Say we have n=10.

All terms are 0 up to (10-1)C(10,10)=9

Regardless the value of n, this is true throughout.

So, the sum is n-1.
9. ## Question: 1+cos theta/2-cos theta

by galactus
2
Views
530

### 1+\frac{cos\theta}{2}-cos\theta is what you have...

1+\frac{cos\theta}{2}-cos\theta is what you have written.

And to do what exactly?
10. ## Question: What is formula pi * are 2 * h / 3,363?

by galactus
33
Views
3,026

### Jjuiibn;j h hmnk mxvnncvuygaefnbamn I...

Jjuiibn;j h hmnk mxvnncvuygaefnbamn

I checked Google and this "problem" has been posted on a dozen different sites. No one else appears to know what it means either.

Especially, the 3363.
11. ## Question: How do you find the radius of half a sphere if you know the diameter

by galactus
2
Views
503

### Same concept as with a circle.

Same concept as with a circle.
12. ## Question: 50 letters

by galactus
2
Views
1,103

### This is known as a derangement. The...

This is known as a derangement.

The probability that no letter ends up in its envelope is

\sum_{k=0}^{N}\frac{(-1)^{k}}{k!}

This is the series for 1/e. So, for large N, the probability...
13. ## Question: Half Life Problem

by galactus
3
Views
618

### There is 12.5 grams out of 50 grams remaining...

There is 12.5 grams out of 50 grams remaining after 14.5 days.

12.5=50e^{k(14.5)}

Solve for k.

Half life is given by:

T=\frac{-ln(2)}{k}
14. ## Question: I tried so hard but I did not get the ans.

by galactus
1
Views
303

### Since the numbers are consecutive, they can be...

Since the numbers are consecutive, they can be written as

x-1, \;\ x, \;\ x+1

The square of the middle number is x^{2}

The difference of the squares of the other two:

(x+1)^{2}-(x-1)^{2}
15. ## Question: Large-Sample Confidence

by galactus
1
Views
214

### The margin of error is E=z\cdot...

The margin of error is E=z\cdot \frac{\sigma}{\sqrt{n}}

.95 CI corresponds to a z score of 1.96

So, we have E=1.96\cdot \frac{4}{\sqrt{30}}=1.43

The CI is then:
...
16. ## Question: Show that 3x^2-y^2+xy=4 is equal to y=2x when the gradient of the tangent is 8/3

by galactus
2
Views
2,065

### Implicitly differentiate 3x^{2}-y^{2}+xy=4 ...

Implicitly differentiate

3x^{2}-y^{2}+xy=4

to get y'.

Set the result = to 8/3 and solve for y.
17. ## Question: Sketch the lemniscate of Bernoulli

by galactus
1
Views
955

Go here and download the very nice and FREE graphing utility. Then, graph it.

Graph

It looks like an infinity symbol.
18. ## Question: Roots problems

by galactus
4
Views
277

### Some explanation from the OP would be nice. But,...

Some explanation from the OP would be nice. But, I assuming those brackets indicate the floor function.

If so, then the first one would be x=0,1,4

I wonder why so many think that those on...
19. ## Question: Math Equation

by galactus
1
Views
210

### \frac{5x^{-2}y^{140}}{256x^{-1}(-3x^{-34}y^{-1})^{...

\frac{5x^{-2}y^{140}}{256x^{-1}(-3x^{-34}y^{-1})^{-67}}

This is not an equation, it is an expression.

Equations have equals signs.

What is it you need to do? Simplify?

First, write with...
20. ## Question: Slove indical equation

by galactus
3
Views
715

### Do you mean 2^{x+2}=4^{-x}? You have...

Do you mean 2^{x+2}=4^{-x}?

You have 2^{x}+2=4^{-x} written.
21. ## Question: How to find inverse of the following function: f(x) = -2 sqrt (-x + 4) -3

by galactus
2
Views
883

### See here as well. ...

See here as well.
22. ## Question: How do you find f(f(g(x)))... If f(x) = 2x+5 and g(x)= square root of x

by galactus
3
Views
1,071

### I will try to decipher. Replace f(x) with...

I will try to decipher.

Replace f(x) with y:

y=k(2+x)

swap x and y:
23. ## Question: Vectors

by galactus
2
Views
498

### A=(0,-1,-1), \;\ B=(4,5,L), \;\ C=(3,9,4), \;\...

A=(0,-1,-1), \;\ B=(4,5,L), \;\ C=(3,9,4), \;\ D=(-4,4,4)

AB=-4i-6k+(-L-1)k

AC=-3i-10j-5k

Cross Product:
24. ## Question: Poisson distribution with parameter lander then E(X)=VAR (X)= LANDER

by galactus
2
Views
924

### Sweet. I would give you a greenie, but it won't...

Sweet. I would give you a greenie, but it won't let me.
25. ## Question: Statistic

by galactus
2
Views
1,049

### a. look up the z score corresponding to a .70 in...

a. look up the z score corresponding to a .70 in the body of the table.

b. same as above only look up .20

c. z scores come from the left and go right. So, just look up .75 in the body of the...
26. ## Question: A banks loan officer rates applicants for credit. The ratings are normally distribute

by galactus
1
Views
1,995

### Go to a z table and look up .60 in the body of...

Go to a z table and look up .60 in the body of the table and find its corresponding z score.

Then, set it equal to the formula z=\frac{x-200}{50}, and solve for x.
27. ## Question: Maths - Lim

by galactus
2
Views
2,033

### This post is 3 years old. And you have the nerve...

This post is 3 years old. And you have the nerve to give me a Not Helpful after posting that nonsense.
28. ## Question: Integration

by galactus
5
Views
802

### I assume then that my interpretation was correct....

I assume then that my interpretation was correct.

The solution is \frac{2010\pi}{2}=1005\pi

Try it with other powers of tan. You will see the solution comes out to half of the upper limit of...
29. ## Question: If ,a=lg(10/9),b=lg(25/24),c=lg(81/80),show that lg2=7a-2b+3c

by galactus
1
Views
697

### 7log(10/9)-2log(25/24)+3log(81/80) Use your...

7log(10/9)-2log(25/24)+3log(81/80)

Use your log laws to break it up and simplify in terms of log(2), log(3), log (5). Everything with cancel except for one little ol' log(2).

For instance, to...
30. ## Question: Integration

by galactus
5
Views
802

### Very good JC. I figured this problem had...

Very good JC. I figured this problem had something to do with observation. This horrific integrals like this normally indicate this. I misread. Either way, good show. Now, let's see if the OP even...
31. ## Question: Integration

by galactus
5
Views
802

### Is this what you mean: ...

Is this what you mean:

\int_{0}^{2010\pi}\frac{1}{tan^{2011}(x)+1}dx

If so, may I ask from where you got this crazy integration problem?

I would venture to say that this is not meant to be...
32. ## Question: Half life equation solver?

by galactus
4
Views
2,298

### An easy way to find your constant of...

An easy way to find your constant of proportionately is to use the formula for half-life:

T=\frac{-ln(2)}{k}

You are given the half-life decay time. Plug it in and solve for k.

Then, you can...
33. ## Question: How to prove that ?

by galactus
2
Views
294

### Look at the factorization for the sum of two...

Look at the factorization for the sum of two cubes.

Factor:

a^{3}+b^{3}

Let a=sin^{2}(x), \;\ b=cos^{2}(x)
34. ## Question: What is the definition of "pi"?

by galactus
19
Views
1,217

### I'm sorry, what do you mean "a developer doing...

I'm sorry, what do you mean "a developer doing some testing"?
35. ## Question: What is the definition of "pi"?

by galactus
19
Views
1,217

### What you posted is the area of a circle. {\pi}...

What you posted is the area of a circle.

{\pi} is the ratio of a circles diameter to its circumference.

In other words. The distance around a circle is Pi, or about 3.14, times the distance...
36. ## Question: Probability problems ?

by galactus
2
Views
533

### Part a is obvious. Part b is the same as...

Part a is obvious.

Part b is the same as asking if a non-leap year starts on a Sunday. There are 7 days in a week. Wouldn't it be 1/7?
37. ## Question: Math

by galactus
3
Views
3,430

### Kudoes, JCaron. I couldn't agree more. I...

Kudoes, JCaron. I couldn't agree more.

I tried giving you a rep, but it will not let me. Some silliness about "spreading it around". I don't know how to take that:)
38. ## Question: Probability hard problems

by galactus
2
Views
432

### Assuming the keys are identical and the boxes are...

Assuming the keys are identical and the boxes are different.

If we are distributing r identical objects into n different boxes, then there are

C(r+n-1,r) ways

In this case, C(5+3-1,5)=21...
39. ## Question: Given the set of digits{2,3,4,7,8,9} how many three-digit numbers can be formed?

by galactus
5
Views
1,448

### If repetition is allowed, then there are ...

If repetition is allowed, then there are

6^{3}=216 numbers that can be formed.

If repetition is not allowed, then there are

6\cdot 5\cdot 4=120 numbers that can be formed.

When forming 3...
40. ## Question: Inverse of composition of a function?

by galactus
1
Views
218

### Assuming they are well-defined, the inverse would...

Assuming they are well-defined, the inverse would be

g^{-1}of^{-1}
41. ## Question: Identify all intercpts of f(x)=x^2+7x+12/x^3+4x^2-x-4

by galactus
1
Views
206

### Here is what you have written: ...

Here is what you have written:

x^{2}+7x+\frac{12}{x^{3}}+4x^{2}-x-4

I assume you mean:

\frac{x^{2}+7x+12}{x^{3}+4x^{2}-x-4}

This is why grouping symbols are important.
42. ## Question: Logarithm equation

by galactus
4
Views
319

### But, if you want to do this algebraically, let''s...

But, if you want to do this algebraically, let''s do this:

Take log of both sides:

log(x^{log(x)-1})=2

(log(x)-1)log(x)=2

(log(x))^{2}-log(x)-2=0
43. ## Question: Logarithm equation

by galactus
4
Views
319

### Yep. That's them. Good :)

Yep. That's them. Good :)
44. ## Question: Logarithm equation

by galactus
4
Views
319

### Is this what you mean?: x^{log(x)-1}=100 If...

Is this what you mean?:

x^{log(x)-1}=100

If so, look close. There are two solutions.One is rather obvious.

What is log(100)? Isn't it equal to 2?

So,...
45. ## Question: How do you get the maximum profits from a cost function?

by galactus
2
Views
1,065

### I assume y is the number of kg produced or sold....

I assume y is the number of kg produced or sold.

Thus, R=160y

Remember, P=R-C

Profit=Revenue-Cost
46. ## Question: What make solution degerate in linear programming

by galactus
3
Views
575

### When a tie happens at least one basic variable...

When a tie happens at least one basic variable will be zero in

the next iteration and the new solution is called 'degenerate'.

Say we wanted to maximize z=3x_{1}+9x_{2}

s.t. ...
47. ## Question: Law of exponents

by galactus
3
Views
227

### Exponent? What exponent? Solve what? Rewrite...

Exponent? What exponent? Solve what?

Rewrite 5 and 3/4 as a decimal? 5.75
48. ## Question: 2x=4

by galactus
2
Views
2,431

### No one is that stupid, so it makes me believe...

No one is that stupid, so it makes me believe this is just a troll with nothing better to do.
49. ## Question: Free math tutorial answer my question?

by galactus
2
Views
1,328

### I assume this is what you're describing?: The...

I assume this is what you're describing?:

The section 1/8th inch on either side of the x-axis must be the same as the segment with height h?

Assuming I am interpreting correctly, find the...
50. ## Question: Log8 1=x

by galactus
1
Views
1,906

### log_{8}(1)=x To write it another way: ...

log_{8}(1)=x

To write it another way:

8^{x}=1

What must x be?
Results 1 to 50 of 500