Math Help

Archive for October, 2007

Question: Math Help Decimals to fractions?

if i have 0.12525252525…. how do i convert it to a fraction?

Answer: x = 0.12525…

<=>

10x = 1.25…

and

1000x = 125.25…

<=>

1000x – 10x = 124

<=>

990x = 124

<=>

x = 124 / 990 <=== answer

http://www.google.fr/search?q=124%2F990&hl=fr&btnG=Recherche+Google

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Math Fractions : Converting Fractions to Decimals

Question: Volume math questions help?

A Rectangular box is 20 cm long, 12 cm wide, and 6 cm high.

What is its volume? ________________
Design a box with twice that volume. What are its dimensions?
______________________________________…

A rectangular box is 16cm long, 10 cm wide, and 8 cm high. What could be the dimensions of a box with one half the volume of this box?
______________________________________…

Please help me

Thanks so much

- Haileyy Jenna

Answer: a box is a rectangular prism, therefore the formula is LxWxH
so 20×12x6= 1440
double that and you get a volume of 2880
it could be a box 8 by 180 by 2, assuming you could have anything as the dimensions.
16x 10 x 8= 1280
1280/2 = 640
it could be 8 by 10 by 8

Volume of a Cylinder – YourTeacher.com – Math Help

Question: Story problem math (linear programming)?

Coyotes need at least 15 units of protein and 20 units of fat per days.

One squirrel provides 5 units of protein and 2 units of fat, but requires 2 units of energy to capture/digest

One cat provides 3 units of protein and 4 units of fat, but requires 3 units of energy to capture/digest

How many of each should the coyote capture/digest in order to meet his daily food reqs and expend the least amount of energy?

Any help would be amazing even if it’s just a starting point.

Answer: Let x and y be the number of squirrels and cats that should be captured/digested by the coyotes.

We want to minimise the amount of energy that the coyotes consumes for capture/digest either squirrels and cats.
i.e., E(x,y)= 2x+3y

subject to the following constriants:
Minimum units of protein required is either equal to or greater than 15, then we have
5x+3y>=15
Minimum units of fats required is either equal to or greater than 20, then we have
2x+4y>=20

x>=0 & y>=0

E(x,y)= 2x+3y
2x+3y = E(x,y)
3y = -2x+E(x,y)
y = (-2/3)x+[E(x,y)/3]
Then, the slope of the above objective function is -2/3.

5x+3y>=15
Let 5x+3y=15.
3y = -5x+15
y = (-5/3)x+5
The slope of this constriant is -5/3.

2x+4y>=20
Let 2x+4y=20.
4y = -2x+20
y = (-2/4)x+5
y = (-1/2)x+5
The slope of this constriant is -1/2.

Since the slope value of the above objective function is -2/3 which lies between the values of the slope of the above two constriants -5/3 and -1/2, then the intersection point of the two constriants is the optimum solution.

Solving simultaneously, we have
5x+3y=15 —Equation 1
2x+4y=20 —Equation 2

From equation 1, multiply both sides by 2, then
10x+6y=30 — Equation 3
From equation 2, multiply both sides by 5, then
10x+20y=100 — Equation 4

Equation 4— Equation 3, then
14y = 70
y = 70/14
y = 5

Substitute y=5 into equation 2, then
2x+4*5=20
2x+20= 20
2x = 20-20
2x = 0
x = 0/2
x = 0

So, the optimum solution is x=0, y=5.

Hope this helps.

Linear Programming