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The 5% bromide "container" I labelled N. The 40% I labelled D (per the instructions of my text).
What I did: I realized that I have two equations: N+d=100 (according to the textbook)which means that n= 100-d ; So I wrote this: ( ) + ( ) = 100 I plugged "n" into the first paranthes, and d into the second. I turned the percents into decimals (5%= 0.5 and 40%= 0.4). I plugged it in, to get:
0.5(N) + 0.4(D) = (100)0.12 (0.12=12%) Since N=100-D, I replaced N with 100-D to get:
0.5(100-D) + 0.4D = 12 I solved to get 50 - 0.5D + 0.4D = 12 --> 50 - .1D =12 ------> Subtracted 50 from both sides to get ----->-.1DN= -38 ----> divided both sides by -.1 ----> and I got 380. Logically, that can't be, because N+D=100. If D = 380 which is greater than 100... What am I doing wrong?!? I've done other problems of this nature, using the SAME process, and they have all been wrong! Please Help!
1 solutions
Answer 272957 by Earlsdon(6287)   on 2010-12-14 11:37:45 (Show Source):
You can put this solution on YOUR website!Try this!
Let x = the required number of ml. of the 5% bromide solution. Then (60-x) will be the required number of ml. of the 40% bromide solution and the sum of these two amounts (x+60-x) will equal the 60 ml. of the final 12% bromide solution.
Here's the equation after changing the percentages to their decimal equivalents:
0.05x+0.4(60-x) = 0.12(60)
Simplify and solve for x.
0.05x+24-0.4x = 7.2 Combine like-terms.
0.05x-0.4x+24 = 7.2
-0.35x+24 = 7.2 Subtract 24 from both sides.
-0.35x = -16.8 Divide both sides by -0.35
x = 48 and 60-x = 12
So you'll need to mix 48 ml. of 5% bromide solution with 12 ml. of 40% bromide solution to obtain 60 ml. of 12% bromide solution.
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test/384758: I am asking this question again because I am just not sure I got it!
line passing thru (3,0) and (-1,-2) slope:1/2
so what is the equation of the line in y=mx+b form
1 solutions
Answer 272382 by Earlsdon(6287) on 2010-12-12 11:19:08 (Show Source):
You can put this solution on YOUR website!The equation of the line passing through the points: (3, 0) and (-1, -2) and having a slope of  in slope-intercept form:  where the slope  .
Start with:
 since you were given the slope, m. To find the value of b, the y-intercept, substitute the x- and y-coordinates from either one of the two given points. Let's choose (3, 0)
Substitute x = 3 and y = 0.
 Simplify.
 Subtract  from both sides.
 Now substitute this into the equation above to get:
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logarithm/384763: Simplify the following expression. Your answer should not contain logarithms.
e^(ln30x^5-ln6x^4)
1 solutions
Answer 272381 by Earlsdon(6287) on 2010-12-12 11:10:16 (Show Source):
You can put this solution on YOUR website!Simplify:
 Simplify the exponent using the quotient rule: 
e^(ln(30x^5/6x^4)) Simplify the argument of the ln in the exponent.
 Recall that:  so...
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test/384757: I asked this question yesterday- but forgot a negative sign, which I do not know what to do with....
(x^9y^-6)^1/3
1 solutions
Answer 272378 by Earlsdon(6287) on 2010-12-12 10:54:45 (Show Source):
You can put this solution on YOUR website!I presume that you want to simplify this expression!
 Remember that:  so...
 Multiply the exponents inside the parentheses by the exponent on the outside to get:
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Polynomials-and-rational-expressions/384605: I am having a nightmare with this one. Can someone please help me.
A 75-ft diagonal brace on a bridge connects a support of the center of the bridge to a side support on the bridge. The horizontal distance that it spans is 15 ft longer that the height that it reaches on the side of the bridge. Find the horizontal and vertical distances spanned by this brace.
1 solutions
Answer 272259 by Earlsdon(6287) on 2010-12-11 21:08:31 (Show Source):
You can put this solution on YOUR website!You could use the Pythagorean theorem  to solve this problem.
You have a right triangle whose hypotenuse is the 75ft. diagonal and whose height is h. The base of this triangle is h+15ft.
You need to find h and h+15.
 Rewrite as a quadratic equation in standard form.
 Divide by 2 to simplify a bit.
 Solve by factoring.
 Apply the zero product rule.
 or 
 or  Discard the negative solution as the height, h, is a positive quantity.
feet. This is the vertical distance.
 feet. This is the horizontal distance.
-----------------------------------------------------
I do hope this takes care of your nightmare!
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Linear_Equations_And_Systems_Word_Problems/384103: Another word problem that has stumped me.
You recently started the paperwork to purchase your new home, and were just notified that you can move into the house in 2 weeks. You decide to hire a moving company, but are unsure which company to choose. You search online and are interested in contacting two companies. Heavy lifting and quick move, to discuss their rates. Heavy lifing chrges an $80 fee plus $35 per hour. Quick Move charges $55 per hour with no additonal fees.
A. which mover provides a better deal for 2 hours of work? How did I arrive at my answer. (clueless)
B. Which mover provided a better deal for 15 hour of work? How did I arrive at that answer?
C. For what values H(hours) does quick Move offer the better deal? Express my answer as an Inequality. Explain hou I reach that answer.
I seem to get mixed up on how to use the right formulas. can you explain each step so I can understand how to do this!
1 solutions
Answer 271935 by Earlsdon(6287) on 2010-12-10 11:07:28 (Show Source):
You can put this solution on YOUR website!Start by assigning a letter to represent the unknown quantity.
Let H = the number of hours.
Now write the two equations for the total cost of of the move by each of the two movers. HL = Heavy lifting and QM = Quick move..
HL = 35H+80
QM = 55H
A) Let H = 2 hours.
HL = 35(2)+80
HL = 70+80
HL = $150
QM = 55(2)
QM = $110
Quick moves is the better choice for 2 hours work.
B) Let H = 15 hours.
HL = 35(15)+80 You can work this out.
QM = 55(15) This one too.
The smallest answer wins.
C) Here you need to find the value of H in the inequality:
QM < HL so...
55H < 35H+80 Solve fo H. Subtract 35H from both sides.
20H < 80 Divide both sides by 20.
H < 4 hours
Quick move is the better deal for moves less than 4 hours.
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Polynomials-and-rational-expressions/383528: What are you really solving for when solving quadratic equations?
1 solutions
Answer 271566 by Earlsdon(6287) on 2010-12-09 09:09:03 (Show Source):
You can put this solution on YOUR website!You are solving for the coordinates on the x-axis where the parabola (the graph of a quadratic equation) intersects the x-axis, if it does intersect it.
You will usually have two different values of x but not always.
If the parabola just touches the x-axis, then you will have a "double" solution in which the two values of the x-coordinate are identical.
If the parabola does not intersect the x-axis, then the solution to the quadratic equation will not be "real" numbers but "complex" numbers of the form 
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logarithm/382936: solve for x: log x + (log x + 21)=2
1 solutions
Answer 271266 by Earlsdon(6287) on 2010-12-08 10:29:17 (Show Source):
You can put this solution on YOUR website!Solve for x:
 Apply the product rule:
 Simplify the argument.
 Rewrite this in exponential form.
 Rewrite as a quadratic equation in standard form.
 Factor.
 Apply the zero product rule.
 or  so...
 or  Discard the negative solution as the log of a negative number is not real.
Check:
 = 
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Mixture_Word_Problems/381898: Hello tudor,
A friend ask me this and so i started helping them. However, i got 160 lb. However, it sounded a bit weird so i want to double check.
How many pounds of seed worth $1.05 per pound must be mixed with 30 pounds of seed worth $.90 per pound in order to produce a mixture to sell for $1.00 per pound?
1 solutions
Answer 270815 by Earlsdon(6287) on 2010-12-06 18:44:17 (Show Source):
You can put this solution on YOUR website!Let x = the number of lbs of seed worth $1.05 per pound.
x($1.05)+30($0.90) = (x+30)($1.00) Simplify and solve for x.
1.05x+27 = x+30 Subtract x from both sides.
0.05x+27 = 30 Subtract 27 from both sides.
0.05x = 3 Finally, divide both sides by 0.05
x = 60lbs.
P.S. I'm not a Tudor nor a Plantaganet.
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Miscellaneous_Word_Problems/380973: Please help me with this one, I think I have the solution but not sure.
An explosion causes debris to rise vertically. The funtion f(t)=-16^2 + 72t describes the height of the debris above the ground, f(t), in feet, t seconds after the explosion.
When does the debris reach its maximum height: I got (-72/-32, 81)
What is the maximum height of the debris: I got (25/2, 81)
When does the debris hit the ground? I got -9/2
When we do these she tells us for the first two to use b/2(a) and then then last one I did the quadratic equation.
Please help me with this so I can work some more on this packet.
Thank you so very much
Tracy
1 solutions
Answer 270349 by Earlsdon(6287) on 2010-12-05 10:30:48 (Show Source):
You can put this solution on YOUR website!First, let's get the equation right!
1) The time to reach maximum height is given by:
 seconds.
2) The maximum height can be found by substituting the time seconds into the given equation.
 Substitute
 Evaluate.
 feet.
3) The time whe debris will hit the ground (  ) can be found by setting the given equation f(t)= 0 and solving for the time, t.
 Factor out a t.
 Now apply the zero product rule:
 or 
The solution is the initial condition.
 Subtract 72 from both sides.
 Divide both sides by -16.
 seconds.
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test/380404: 2 pipes are connected to a tank. On pipe fills the tank in 7 hours. The second pipe empties the tank in 9 hours. If both pipes are open, how long will it take to fill the tank?
1 solutions
Answer 269974 by Earlsdon(6287) on 2010-12-03 18:36:12 (Show Source):
You can put this solution on YOUR website!Find the hourly rate of each event.
If the first pipe can fill the tank in 7 hours, then it can fill (+)  of the tank in 1 hour.
If the second pipe can empty the tank in 9 hours, then it can empty (-)  of the tank in 1 hour.
Putting these two events together, we get:
So  of the tank is filled in 1 hour.
It takes  hours to fill the tank.
 hours.
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Quadratic_Equations/380058: I need help! This is due tomorrow! (It's 7th grade math by the way.)
The question says: Write an equation to find the value of x so that each pair of polygons has the same perimeter. Then solve.
1. A triangle has sides that say: x+6, x+9, and x+3. A rectangle beside it has sides that say x+4 and x+1.
2. A hexagon has sides that all read 5x. A triangle next to it has sides that say x+14, x+17, and 8x+9.
PLEASE help me!
1 solutions
Answer 269753 by Earlsdon(6287) on 2010-12-02 21:35:35 (Show Source):
You can put this solution on YOUR website!1) For the triangle, let the perimeter = P, then...
(x+6)+(x+9)(+x+3) = P Simplify.
3x+18 = P
For the rectangle, let the perimeter = P (the same P), then...
2(x+4)+2(x+1) = P Simplify.
2x+8+2x+2 = P
4x+10 = P Now, because P = P you set these two equations equal and solve for x...
3x+18 = 4x+10 Subtract 3x from both sides.
18 = x+10 Now subtract 10 from both sides.
8 = x or x = 8.
Now you can apply this to the next problem.
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Triangles/377826: All sides of a triangle are integers. If the length of 2 sides are 7 and 5, what is the largest possible perimeter?
I think it is 24, but there is no answer like that in the multiple choice. The teacher might have made a mistake(she admitted it herself) but I want to be completely sure that my answer 24 is correct before telling her of her mistake.
Thank you very much.
1 solutions
Answer 268456 by Earlsdon(6287) on 2010-11-29 18:50:36 (Show Source):
You can put this solution on YOUR website!Imagine this:
If you were to lay the two given sides flat so they form a single contiguous straight line, this line would be 12 (5+7) units long. Now you could not possibly make a triangle by adding a third side of 12 units, it would have to be shorter than 12 in order to make a triangle and, since you are dealing with integral sides, the third side could be no longer than 11 units, making the maximum perimeter 7+5+11 = 23 units.
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Expressions-with-variables/377082: I need help with 382+x divided by 3=227 (382+x is all divided by 3). I know the answer is 299, but can figure out how to show it. The 299 was a guess that turned out right.
Thanks,
Denise
1 solutions
Answer 268060 by Earlsdon(6287) on 2010-11-28 16:08:27 (Show Source):
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Percentage-and-ratio-word-problems/376445: HOw many oz. of a metal containing 66% silver must be combined with 3 oz. of a metal containing 90% sivler to form an alloy containing 85% silver?
1 solutions
Answer 267825 by Earlsdon(6287) on 2010-11-27 09:31:24 (Show Source):
You can put this solution on YOUR website!How much silver is there in the alloys?
Let x = the number of oz of 66% silver alloy.
This contains (0.66)x oz of silver.
The 3 oz of 90% silver alloy contain (0.9)(3) oz of silver.
The sum of these is to equal (3+x)(0.85) oz of silver.
We can write the equation to solve for x.
0.66x+0.9(3) = 0.85(3+x) Simplify and solve for x.
0.66x+2.7 = 2.55+0.85x Subtract 0.66x from both sides.
2.7 = 2.55+0.19x Subtract 2.55 from both sides.
0.15 = 0.19x Finally, divide both sides by 0.19
x = 0.789 oz of the 66% silver alloy will be required.
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Functions/376055: Just need confirmation on some answers I have for this problem
Find the indicated outputs for f(x) = 2 x^2-2x
F (0) = I need to replace the variable x with 0. My answer is 0.
f(-1) = I need to replace x with -1. My answer is 0.
f(2) = Replaced with 2. My answer is 4.
1 solutions
Answer 267468 by Earlsdon(6287) on 2010-11-25 10:51:55 (Show Source):
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Quadratic_Equations/375874: I am having trouble wiyh my Appendix F. Can someone help me please?
Suppose you are an event coordinator for a large performance theater. One of the hottest new Broadway musicals has started to tour, and your city is the first stop on the tour. You need to supply information about projected ticket sales to the box office manager. The box office manager uses this information to anticipate staffing needs until the tickets sell out. You provide the manager with a quadratic equation that models the expected number of ticket sales for each day x. ( is the day tickets go on sale).
Tickets = x2 - 6x + 16
a. Does the graph of this equation open up or down? How did you determine this?
b. Describe what happens to the tickets sales as time passes?
c. Use the quadratic equation to determine the last day that tickets will be sold. (Note: Write your answer in terms of the number of days after ticket sales begin.)
d. Will tickets peak or be at a low during the middle of the sale? How do you know?
e. After how many days will the peak or low occur?
f. How many tickets will be sold on the day when the peak or low occurs?
g. What is the point of the vertex? How does this number relate to your answers in parts e and f?
h. How many solutions are there to the equation x2 - 6x + 16? How do you know?
i. What do the solutions represent? Is there a solution that does not make sense? If so, in what ways does the solution not make sense?
1 solutions
Answer 267345 by Earlsdon(6287) on 2010-11-24 18:35:53 (Show Source):
You can put this solution on YOUR website!Well, I'm sorry to hear that you're having trouble with your appendix but you really should see a doctor, it might be appendicitis.
But back to the problem:
Given the equation for expected ticket sales (T):
a) The graph opens up. You know (or should know) this because the coefficient of the  term is positive (+1). If it were negative, the graph would open down.
b) The number of tickets, T, first goes down until day 3 (x = 3), then it goes up.
c) There's no way to answer this question without first knowing how many tickets were for sale to begin with. This information was not provided.
d) Since the graph opens up, the vertex is a minimum and the tickets will be at a low, but whether this is at the middle of the sale cannot be determined since you have not provided the total number of tickets for sale.
e) The minimum (low) occurs at 3 days (x=3).
f) The number of tickets, T, sold at day 3 is 7 (T = 7 when x = 3).
g) The point of the vertex is (3, 7) and this is determined either from the graph or algebraically:
Find the x-coordinate by:
 Now plug this into the quadratic eqation to find y (or T in this problem)
 Evaluate.
The vertex is at (3, 7)
h) There are two solutions to the given quadratic equation. The number of solutions is equal to the highest power of the independent variable (x) which is 2 in this problem.
i) The solutions to this equation are not real numbers so they are meaningless.
 and 
The solutions are meaningless because the graph never intersects the x-axis indicating that the number of tickets sold never reaches zero.
In the graph, T (Expected number of tickets sold)is the vertical axis and x (Days after start of sale) is the horizontal axis.
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Exponents/375918: Hi there, I'm being asked to evaluate the following:
 for k = 1 through k = 4
I plugged 1 through 4 into the equation and ended up with this equation:
I'm just checking myself, this is new to me but seems relatively simple. Thanks for your help and have a great holiday!
1 solutions
Answer 267338 by Earlsdon(6287) on 2010-11-24 17:39:03 (Show Source):
You can put this solution on YOUR website!Am I missing something here?
How did you start with  (no x's) and end up with 
Have you mixed up two different problems?
Anyway, back to the original question:
Evaluate  for k = 1 through 4.
Start with k=1.
 = 
Now k=2.
 = 
Now you should be able to finish this by following the examples above.
Good luck!
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Linear_Equations_And_Systems_Word_Problems/375493: The intensity I of a television signal varies inversely as the square of distance d from the transmitter. If the intensity is 25W/m^2 at a distance of 2 km, how far from the transmitter are you when the intensity is 2.6W/m^2?
Unfortunately, we did not go over this in class so I've been struggling with trying to figure it out. I want to think the formula to start with is I = k/d^2 after that I am stumped. I don't understand what 2.6W/m^2 represents.
Any help would greatly be appreciated.
1 solutions
Answer 267072 by Earlsdon(6287) on 2010-11-23 17:00:23 (Show Source):
You can put this solution on YOUR website!You are off to a good start! You have written the inverse variation function for intensity (I):
 Now you need to find the value of k, the constant of variation. You do this by substituting the given values of  W/m^2 and  meters:
 so that...
 Now the function for intensity looks like:
 Now you can answer the question posed in the problem:
"How far (d) are you from the transmitter when the intensity (I) is 2.6W/  ?
Substitute the values into the last equation:
 Solve for  .
 Take the square root of both sides.
 meters.
 meters.
Intensity is Watts per square meter or 
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Length-and-distance/375422: Hi
I asked for help before on this question and no one responded. I know its because its confusing. The problem is a trapazoid. The question is find volume in cubic feet. Here's my problem. The diagram only has one base(lower base) 25 feet. The shorter side is 9 feet and the longer side is 16 feet. and I think the three dimensional side to the right of the diagram is considered the depth? this is 18 feet. I know the formula for a trapezoid A=1/2 h (a+b)= but I'm not sure if I did 1/2 . 16.(25 + 9 )
1/2 . 16 .( 34 )
1/2. 544 = 270 is correct. Do you multiply that by 18
or is the whole problem WRONG because I"m not using a upperbase because I don't know what the upperbase is??? In the problem she gave us there are only four sets of numbers. 9 feet side, 16 feet side 25 feet base and 18 feet depth. It does not have a number for the upperbase. So I'm totally lost. Can anyone help please???? Thank You ever so much.
Janet
1 solutions
Answer 266996 by Earlsdon(6287) on 2010-11-23 13:01:15 (Show Source):
You can put this solution on YOUR website!Janet, the best I can do with your description is the following:
It looks like you have a three-dimensional solid with one face in the shape of a trapezoid.
The trapezoid has dimensions of:
Base = 25ft.
Left side (perpedicular to the base) = 9ft.
Right side (perpendicular to the base) = 16ft.
Now extend this trapezoid shape 18ft. (We'll call this the "depth" of the solid) away from, but perpendicular to, the 25ft. base.
To find the volume of this solid, first find the area of the trapezoid.
 Substitute  ,  , and 
 sq.ft.
Now find the volume by multiplying the area of the trapezoid (312.5sq.ft.) by the "depth" (18ft.).
 cu.ft.
I hope I have interpreted your description correctly.
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