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The attendant checks the machine and finds a total of 42 coins whose value is $3.40. How many coins of each type were there?
1 solutions
Answer 111421 by checkley77(12569)   on 2008-08-11 10:39:13 (Show Source):
You can put this solution on YOUR website!D+N=42 OR D=42-N
.10D+.05N=3.40
.10(42-N)+.05N=3.40
4.20-.10N+.05N=3.40
-.05N=3.40-4.20
-.05N=-.80
N=-.80/-.05
N=16 NUMBER OF NICKELS.
42-16=26 NUMBER OF DIMES.
PROOF:
.10*26+.05*16=3.40
2.6+.80=3.40
3.40=3.40
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Linear_Equations_And_Systems_Word_Problems/151574: The length of the longest side of a triangle is twice the length of the shortest side. The length of the middle-sized side is five more than the length of the shortest side. Find the lengths of the sides of the triangle if the perimeter is 33 feet. Draw and label a picture representing this solution.
1 solutions
Answer 111419 by checkley77(12569) on 2008-08-11 10:28:54 (Show Source):
You can put this solution on YOUR website!.10X+.02*40=.05(40+X)
.10X+.8=2+.05X
.10X-.05X=2-.08
.05X=1.2
X=1.2/.05
X=24 OZ. OF 10% BAKING SODA MUST BE ADDED.
PROOF:
.10*24+.02*40=.05(40+24)
2.4+.8=.05*64
3.2=3.2
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Geometry_Word_Problems/151589: The length of the longest side of a triangle is twice the length of the shortest side. The length of the middle-sized side is five more than the length of the shortest side. Find the lengths of the sides of the triangle if the perimeter is 33 feet.
1 solutions
Answer 111417 by checkley77(12569) on 2008-08-11 10:22:38 (Show Source):
You can put this solution on YOUR website!LONGEST SIDE=2X
SHORTEST SIDE=X
MIDDLE SIDE=X+5
2X+X+X+5=33
4X=33-5
4X=28
X=28/4
X=7 FOR THE SHORTEST SIDE.
7+5=12 FOR THE MIDDLE SIDE
2*7=14 FOR THE LONGEST SIDE.
PROOF:
7+12=14=33
33=33
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logarithm/151505: This question is from textbook precalculus
Example 4 on page 352 shows how to do this problem, but I am having problems factoring once I get to the point of setting the 2-x-x^2>0 and then solving for x (factoring is one of my major weaknesses). I seem to have trouble with factoring whenever I am faced with needing to combine the same variable in two different forms (e.g. the -x-x^2). Thanks.
1 solutions
Answer 111374 by checkley77(12569) on 2008-08-10 16:08:58 (Show Source):
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Money_Word_Problems/151434: Find the interest earned at the end of the first year on 6,800. invested at 4% I started with I=0.4x1/12=6800 then is it0.4 /12=6800/12 I am stuck
1 solutions
Answer 111373 by checkley77(12569) on 2008-08-10 16:01:54 (Show Source):
You can put this solution on YOUR website!YOU HAVE THE WRONG FORMULA.
I=PR^T WHERE I=INTEREST, P=PRINCIPLE, R=ANNUAL % RATE, T=NUMBER OF YEARS.
I=6,800*.04^1
I=$272 IS THE INTEREST AT THE END OF 1 YEAR.
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Linear_Algebra/151459: 1. Solve for X and Y in the following problems. Make sure you show all your work so you can get partial credit even if your final answer is wrong.
a. X + Y=7 , X + 2Y = 11
b. 3X + 7Y = 24, 9X + 5Y = 24
c. 4X + Y = 17, 2X + 3Y = 21
d. 18X + Y = 42, 6X - 3Y = -6
1 solutions
Answer 111372 by checkley77(12569) on 2008-08-10 15:44:58 (Show Source):
You can put this solution on YOUR website!I'LL DO THE FIRST 2 TO SHOW YOU HOW IT'S DONE.
THE LAST 2 ARE FOR YOU TO PRACTICE WITH NOW THAT YOU HAVE THE PROCEDURE.
--------------------------------------------------------------------
a)X + Y=7
X + 2Y = 11 SUBTRACT.
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-Y=-4
Y=4 ANSWER.
X+4=7
X=7-4
X=3 ANSWER.
PROOF
3+2*4=11
3+8=11
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b)3X + 7Y = 24 MULTIPLY BY -3 & ADD.
9X + 5Y = 24
-9X-21Y=-72 ADD.
---------------
-16Y=-48
Y=-48/-16
Y=3 ANSWER.
9X+5*3=24
9X+15=24
9X=24-15
9X=9
X=9/9
X=1 ANSWER.
PROOF:
3*1+7*3=24
3+21=24
24=24
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test/151471: if you osve this,can you please break down the steps and explain what to do because i dont know what to do when you 3 equations like these:
A=11B
A+x=5(B+x)
A+x+5=3(B+x+5)
1 solutions
Answer 111369 by checkley77(12569) on 2008-08-10 15:30:17 (Show Source):
You can put this solution on YOUR website!First you replace A by 11B in the remaing 2 equations.
A+x=5(B+x)
11B+x=5(B+x)
11B+x=5B+5x
x-5x=5B-11B
-4x=-6B (EQUATION #1)
A+x+5=3(B+x+5)
11B+x+5=3(B+x+5)
11B+x+5=3B+3x+15
x-3x=-11B+3B+15
-2x=-8B+15 (EQUATION #2)
MULTIPLY THIS EQUATION BY -2 & ADD IT TO EQUATION #1.
4X=16B-30
-4x=-6B
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0=10B-30
10B=30
B=30/10
B=3 ANSWER.
A=11*3
A=33 ANSWER.
-4x=-6*3
-4x=-18
x=-18/-4
X=4.5 ANSWER.
PROOF
33+4.5=5(3+4.5)
37.5=5*7.5
37.5=37.5
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Mixture_Word_Problems/151483: Please help me my friends all have the same answer but I don't.
7.)How many quarts of a 60% alcohol solution must be added to 40 quarts of a 20% alcohol solution to obtain a mixture whic is 30% alcohol? All percentages are by volume.
6.) What weight of water must be evaporated from 40lb of a 20% salt solution to produce a 50% solution? All percentages are by weight.
thank you
1 solutions
Answer 111365 by checkley77(12569) on 2008-08-10 15:13:09 (Show Source):
You can put this solution on YOUR website!7) .6x+40*.2=.3(40+x)
.6x+8=12+.3x
.6x-.3x=12-8
.3x=4
x=4/.3
x=13.33 quarts of 60% alcohol is needed.
proof:
.6*13.33+8=.3(40+13.33)
8+8=.3*53.33
16=16
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6) 40*.2=8 pounds of salt.
For a 50% solution you need 2*8=16 pounds of water.
40-16=24 pounds of water must be evaporated.
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Geometry_Word_Problems/151445: a developer wants to enclose a rectangular lot that borders a city street. if the developer has 248ft of fence and DOES NOT fence the side bordering the street, what is the largest area that can be enclosed?
1 solutions
Answer 111327 by checkley77(12569) on 2008-08-10 09:28:21 (Show Source):
You can put this solution on YOUR website!TO SOLVE THESE PROBLEMS JUST DIVIDE THE TOTAL LENGTH BY 3.
248/3=62 THIS IS THE SHORT SIDES OF THE FENCE.
THE REMAINING FENCE (248-2*62)=248-124=124 IS THE LONG SINGLE SIDE.
PROOF;
62*124=7,688 SQUARE FT. IS THE LARGEST AREA.
TRY A SQUARE BY DIVIDING THE FENCE LENGTH BY 3.
248/3=82.67
NOW SQUARE 62.67^2=6,834 SQUARE FT.
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Travel_Word_Problems/151407: A freight train takes 2 hours longer to travel 300 miles than an express train to travel 280 miles. The rate of the express train is 20mph greater than the rate of the freight train. Find the time for the express train.
Please help!
1 solutions
Answer 111302 by checkley77(12569) on 2008-08-09 18:20:34 (Show Source):
You can put this solution on YOUR website!300=r(t+2)
r=300/(t+2)
280=(r+20)t
280=(300/(t+2)+20)t
280=300t/(t+2)+20t
280=(300t+20t(t+2))/(t+2)
280(t+2)=300t+20t^2+40t
280t+560=340t+20t^2
20t^2+340t-280t-560=0
20t^2+60t-560=0
20(t^2+3t-28)=0
20(t+7)(t-4)=0
t-4=0
t=4 hours for the express train
280=4(r+20)
280=4r+80
4r=280-80
4r=200
r=200/4
r=50 mph is the rate of the freight train.
proofs:
300=50(4+2)
300=300
280=(50+20)*4
280=70*4
280=280
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Travel_Word_Problems/151403: I am having difficulty setting up this word problem. If a taxi charges .50 for the first 1/5 of a mile, and .20 for every 1/10 of a mile after that, how much would it cost to go 2 miles?
1 solutions
Answer 111300 by checkley77(12569) on 2008-08-09 17:39:40 (Show Source):
You can put this solution on YOUR website!1/5 mile=.50
2-1/5=1 4/5 mile or 9/5 or 18/10 miles.
18*.20=3.60 for the rest of the 2 mile ride.
Thus the total for the 2 mile ride=.50+3.60=$4.10
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Graphs/151408: You are told that a line has a slope of -3 / 4 and that the line passes through the point given by ( -2, 3 ). Choose two other points from those given below which are on this same line.
1 solutions
Answer 111299 by checkley77(12569) on 2008-08-09 17:34:29 (Show Source):
You can put this solution on YOUR website!SLOPE=-3/4
POINT=(-2,3)
4=-3/4*-3+b
4=9/4+b
b=4-9/4
b=(16-9)/4
b=7/4
ANOTHER POINT IS (0,7/4)
THUS THE EQUATION OF THIS LINE IS:
Y=-3X/4+7/4
 (graph 300x200 pixels, x from -6 to 5, y from -10 to 10, -3x/4 +7/4).
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Rectangles/151409: If the perimeter is 210 yards and the area is 2250 square yards, what are the dimensions?
1 solutions
Answer 111298 by checkley77(12569) on 2008-08-09 17:28:46 (Show Source):
You can put this solution on YOUR website!sORRY i DIDN'T NOTICE THE RECTANGLE IN THE 'Move to a better place box'.
XY=2250
X=2250/Y
2(2250/Y)+2Y=210
4500/Y+2Y=210
(4500+2Y*Y)/Y=210
4500+2Y^2=210Y
2Y^2-210Y+4500=0
2(Y^2-105+2250)=0
2(Y-75)(Y-30)=0
Y-75=0
Y=75
Y-30=0
Y=30
Y=75 THEN X=30
Y=30 THEN X=75
PROOF:
2*75+2*30=210
150+60=210
75*30=2250
2250=2250
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Geometry_Word_Problems/151410: can someone help me with this word problem? i have tried everything, but i just cant seem to figure it out...
three circles have to be cut into a piece of metal. the specifications state that each of the diameters must be within 0.001 centimeter of the given measurements. let D represent the given measurement and let x respresent the actual diameter of the circle. write an absolute value inequality that descrides the acceptible diameters of the circle. if the circles are to be 13 centimeters, 9 centimeters, nad 6 centimeters, describe the acceptable diameters of each circle.
1 solutions
Answer 111296 by checkley77(12569) on 2008-08-09 17:14:00 (Show Source):
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logarithm/151170: using formula w=0.00185h^2.67 where w is a boy's weight in pounds and h is his height in inches, estimate the height of a boy whose weight is 100 pounds.
1 solutions
Answer 111213 by checkley77(12569) on 2008-08-08 16:39:10 (Show Source):
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Linear-equations/151240: x/4 - y/11 = -9/44
x/6 - y/13 = -1/26
1 solutions
Answer 111133 by checkley77(12569) on 2008-08-07 19:43:30 (Show Source):
You can put this solution on YOUR website!x/4 - y/11 = -9/44
(11X+4Y)/44=-9/44 DIVIDE BOTH SIDES BY 1/44.
11X-4Y=-9
x/6 - y/13 = -1/26
(13X-6Y)/84=-1/26 DIVIDE BOTH SIDES BY 1/26.
(13X-6Y)/3=-1
13X-6Y=-3 NOW MULTIPLY THIS EQUATION BY 2 & MULTIPLY THE OTHER EQUATION BY -3 & ADD THEM:
26X-12Y=-6
-33X+12Y=27
------------------------
-7X=21
X=21/-7
X=-3 ANSWER.
11*-3-4Y=-9
-33-4Y=-9
-4Y=-9+33
-4Y=24
Y=24/-4
Y=-6 ANSWER.
PROOF:
-3/6-(-6/13)=-1/26
-1/2+6/13=-1/26
(-13+12)/26=-1/26
-1/26=-1/26
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Polynomials-and-rational-expressions/151143: 5 3
____ + ______ =⅔
x – 1 7X – 7
1 solutions
Answer 111131 by checkley77(12569) on 2008-08-07 19:20:34 (Show Source):
You can put this solution on YOUR website!5 3
____ + ______ =2/3
x – 1 7X – 7
[5(7X-7)+3(X-1)]/(X-1)(7X-7)=2/3
[35X-35+3X-3]/(7X^2-14X+7)=2/3
2(7X^2-14X+7)=3(38X-38)
14X^2-28X+14=114X-114
14X^2-28X-114X+14+114=0
14X^2-142X+128=0
2(7X^2-71X+64)=0
2(7X-64)(X-1)=0
7X-64=0
7X=64
X=64/7
X=9.1428 ANSWER.
X-1=0
X=1 NOT A VALID ANSWER BECAUSE THIS WOULD REQUIRE DIVIDING BY 0.
PROOF
5/(9.1428-1)+3/(7*9.1428-7)=2/3
5/8.1428+3/(64-7)=2/3
.614+3/57=2/3
.614+.0526=2/3
.666=.666
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