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Systems-of-equations/584955: solution to algebra problem
n/2=n+1
please explain answer steps
1 solutions

Answer 372997 by solver91311(16868) About Me  on 2012-03-09 18:48:02 (Show Source):
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Multiply both sides by 2.

Add -2n to both sides.

Multiply both sides by -1.

John

My calculator said it, I believe it, that settles it
The Out Campaign: Scarlet Letter of Atheism



Matrices-and-determiminant/584954: Find the value of the determinant
|-6 -6|
|b a|
1 solutions

Answer 372995 by solver91311(16868) About Me  on 2012-03-09 18:46:08 (Show Source):
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Product of the elements in the down diagonal:

Product of the elements in the up diagonal:

Down Diagonal minus the up diagonal:

John

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The Out Campaign: Scarlet Letter of Atheism



Probability-and-statistics/584901: a number cube is rolled one time and the result is recorded. The same number cube is rolled a second time. What is the probablitiy that the sum of the rolls is greater than 7?
1 solutions

Answer 372973 by solver91311(16868) About Me  on 2012-03-09 15:57:27 (Show Source):
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There are 5 ways to make 8, 4 ways to make 9, 3 ways to make 10, 2 ways to make 11 and 1 way to make 12. 5 plus 4 plus 3 plus 2 plus 1 is 15 ways to achieve success out of 36 total outcomes.

John

My calculator said it, I believe it, that settles it
The Out Campaign: Scarlet Letter of Atheism



Geometry_Word_Problems/584918: One evening 1500 concert tickets were sold. Tickets cost $20 for pavillion seats and $15 for lawn seats. Total receipts were $27,500. How many tickets of each type were sold?
1 solutions

Answer 372972 by solver91311(16868) About Me  on 2012-03-09 15:53:56 (Show Source):
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Solve the 2X2 system. Substitution is probably the best method in this case.

John

My calculator said it, I believe it, that settles it
The Out Campaign: Scarlet Letter of Atheism



Surface-area/584883: Prism A and prism B are similar. If prism A has length 5 feet and width 8 feet and prism B has length 7.5 feet, what is the width of prism B?
1 solutions

Answer 372971 by solver91311(16868) About Me  on 2012-03-09 15:51:51 (Show Source):
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Calculate , then calculate

John

My calculator said it, I believe it, that settles it
The Out Campaign: Scarlet Letter of Atheism



Travel_Word_Problems/584916: A plane takes off traveling east at 175mph. A jet takes off from the same airport, also traveling east, 2 hours later at 315 mph. When will the jet overtake the airplane?
1 solutions

Answer 372968 by solver91311(16868) About Me  on 2012-03-09 15:44:17 (Show Source):
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In the first 2 hours, the (presumably non-jet) plane will have travelled 350 miles (2 hours times 175 mph). The jet is travelling 315 minus 175 = 140 mph faster. How long will it take to cover 350 miles at 140 mph?

John

My calculator said it, I believe it, that settles it
The Out Campaign: Scarlet Letter of Atheism



Volume/584891: A rectangular prism has edges of 2, 3, and 4 cm. If each edge is increased by 50%, by what factor is the volume increased? Please show me how to do it
1 solutions

Answer 372967 by solver91311(16868) About Me  on 2012-03-09 15:39:47 (Show Source):
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Long (lots of arithmetic) way: Multiply the original length times width times height to get the original volume. Multiply each of the original dimensions by 1.5 to get the new dimensions. Multiply the new length times new width times new height to get the new volume. Divide the new volume by the old volume.

Short way: Calculate

John

My calculator said it, I believe it, that settles it
The Out Campaign: Scarlet Letter of Atheism



Miscellaneous_Word_Problems/584902: A nutrition class last 40 minutes. What frational part of an hour is the nutrition class?
1 solutions

Answer 372961 by solver91311(16868) About Me  on 2012-03-09 15:24:10 (Show Source):
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You will need to reduce the fraction.

John

My calculator said it, I believe it, that settles it
The Out Campaign: Scarlet Letter of Atheism



Points-lines-and-rays/584911: Hi id like some help with this question here:
A triangle has vertices A(11,1) B(3,6) and C(3,-4)
Find an equation of the line that is parallel to AB and contains point C.
I think it was (-2,-2)(3,-4)
1 solutions

Answer 372960 by solver91311(16868) About Me  on 2012-03-09 15:22:19 (Show Source):
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Parallel lines have identical slopes. Use the slope formula:



where and are the coordinates of the given points A and B.

Then use the point-slope form of an equation of a line:



where are the coordinates of point C and is the slope calculated above.

John

My calculator said it, I believe it, that settles it
The Out Campaign: Scarlet Letter of Atheism



Triangles/584906: a right isosceles triangle has legs of length 12cm. what is the length of its hypotenuse? Express your anwser in simples radical form
1 solutions

Answer 372959 by solver91311(16868) About Me  on 2012-03-09 15:17:58 (Show Source):
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The measure of the hypotenuse of an isosceles right triangle with legs that measure is

John

My calculator said it, I believe it, that settles it
The Out Campaign: Scarlet Letter of Atheism



Polygons/584907: What is the sum of the measures of the interior angles in a 74-gon?

1 solutions

Answer 372958 by solver91311(16868) About Me  on 2012-03-09 15:15:26 (Show Source):
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The sum of the measures of the interior angles of an -gon is given by degrees. Put in 74 for and do the arithmetic.

John

My calculator said it, I believe it, that settles it
The Out Campaign: Scarlet Letter of Atheism



Miscellaneous_Word_Problems/584850: Two sandboxes, one with black sand and one with white sand, each contain the same amount of sand. You scoop a full bucket of black sand and pour it into the white sand. Trying to avoid doing your algebra homework, you stir the mixture for hours and hours until the black and white sand are perfectly mixed. You then scoop a full bucket of the mixed sand and pour it into the black sand so that both sandboxes once again have the same amount of sand.
Which is greater, the amount of black sand added to the white sand or the amount of white sand added to the black sand, or are they equal? Be sure to fully explain your reasoning with a mathematical example.
1 solutions

Answer 372954 by solver91311(16868) About Me  on 2012-03-09 15:05:17 (Show Source):
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Let represent the amount of black sand originally in the black sandbox, and let represent the amount of black sand in one full bucket of black sand. Likewise, let and represent analogous quantities of white sand.

Before anything happens, there are units of black sand in the black sandbox and units of white sand in the white sandbox. After the one bucket of black sand is taken from the black sandbox and added to the white sandbox, the black sandbox will contain units of black sand and the white sandbox will contain units of white sand plus units of black sand.

After the white sandbox has been "perfectly" mixed and a full bucket of mixed sand is taken out, the bucket will (because the mixture is "perfect") contain exactly units of mixed sand and the formerly white but now mixed sandbox will contain units of mixed sand (because half a bucket each of white and black were taken away -- the white from what was already there at the start and the black from the whole bucket of black that was added).

When the bucket of mixed is added back to the black sandbox, now there is in the formerly black sandbox; half a bucket of black being returned leaving a deficit of half a bucket of black and half a bucket of new white sand that has been added.

So the amount of black added to the white is equal to the amount of white added to the black.

Super Double Plus Extra Credit:

Let's say you didn't bother spend the "hours and hours" to get the "perfect" mixture. Instead, you just dump the bucket of black sand into the white sandbox and then scoop up a bucketful of the white sandbox contents at random such that anywhere from 0 to 100% of the bucket contains black sand. After you dump the contents in the black sandbox, answer the "Which is greater..." question again.

John

My calculator said it, I believe it, that settles it
The Out Campaign: Scarlet Letter of Atheism



Sequences-and-series/584818: My grade in a certain math class is determined by three tests. My highest test score will count for 50%
of my grade and my lowest for 20%; the "middle" test score will count for 30%. I must have a weighted
average of 60 in order to pass the class. If I have already earned scores of 70 on my first two tests,
what is the lowest score I can earn on the third test for which I will still pass the class?
1 solutions

Answer 372923 by solver91311(16868) About Me  on 2012-03-09 13:07:20 (Show Source):
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If you score greater than 70 on the third test, then obviously the weighted average will be greater than 70, hence the minimum score on the third test in order to reach a weighted average of 60 must be a score less than 70. That means that the top and middle scores will, in fact, be 70.

So, your weighted average will be:



Where is the score on the third test.

Solve



for

Super Double Plus Extra Credit: True or False: If the scores on the first two tests had been 75, you could sleep in the day of the test.

John

My calculator said it, I believe it, that settles it
The Out Campaign: Scarlet Letter of Atheism



Graphs/584821: Find the slope of the line through (5,8) and (-1,6)
1 solutions

Answer 372901 by solver91311(16868) About Me  on 2012-03-09 11:48:31 (Show Source):
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Use the slope formula:



where and are the coordinates of the given points.

John

My calculator said it, I believe it, that settles it
The Out Campaign: Scarlet Letter of Atheism



Functions/584823: is the function y=3x+4 a proportional function?

1 solutions

Answer 372900 by solver91311(16868) About Me  on 2012-03-09 11:47:24 (Show Source):
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Since it is a linear function, it is a directly proportional function.

John

My calculator said it, I believe it, that settles it
The Out Campaign: Scarlet Letter of Atheism



Travel_Word_Problems/584824: How much gas would it take to go 1100 miles in a Chevy aveo
1 solutions

Answer 372899 by solver91311(16868) About Me  on 2012-03-09 11:45:41 (Show Source):
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Same answer as I gave to the one you asked about the van.

John

My calculator said it, I believe it, that settles it
The Out Campaign: Scarlet Letter of Atheism



percentage/584825: if i took a test and got 48 out of 51 questions correct what is the percentage of questions i got correct
1 solutions

Answer 372898 by solver91311(16868) About Me  on 2012-03-09 11:44:16 (Show Source):
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Divide 48 by 51. Move the decimal point two places to the right. Round to a level of precision appropriate to your intended use of the answer. If you answered 48 questions out of 51 correctly, the test probably didn't cover the subjects of grammar, punctuation, and capitalization.

John

My calculator said it, I believe it, that settles it
The Out Campaign: Scarlet Letter of Atheism



Travel_Word_Problems/584819: How much gas would it take to go 144 miles in a van
1 solutions

Answer 372897 by solver91311(16868) About Me  on 2012-03-09 11:40:46 (Show Source):
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144 divided by the number of miles per gallon achieved by that particular van. The achieved mpg is effected by many factors: The size and type of engine, weight of the loaded vehicle, the material condition of the vehicle, including the engine and drive train, the inflation of the tires, the road conditions, the average speed over the trip, the particular driver's skill (or lack thereof), etc., ad infinitum, ad nauseum. In other words, even though there is no such thing as a stupid question asked by a student, you just got closer than anyone I have ever known.

John

My calculator said it, I believe it, that settles it
The Out Campaign: Scarlet Letter of Atheism



Exponential-and-logarithmic-functions/584809: Natural logarithms question : In3x=8
1 solutions

Answer 372896 by solver91311(16868) About Me  on 2012-03-09 11:33:32 (Show Source):
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so





John

My calculator said it, I believe it, that settles it
The Out Campaign: Scarlet Letter of Atheism



Length-and-distance/584671: I am homeschooled and have only one instructor who I cannot get in touch with often since our schedules conflict and time zones are off. I really need help with this problem. Can you explain how to simplify? I can't find explanation anywhere in my online text for this and I know or at least think that length times width would give me an answer but don't know about converting yards and feet. The choices I have for answers never match what I come up with. Here is the question: A rectangular patio is 9 yd 2 ft long and 5 yd 2 ft wide. What is the perimeter of the patio in yards? Thank you!
1 solutions

Answer 372834 by solver91311(16868) About Me  on 2012-03-08 23:41:22 (Show Source):
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Length times width gives you the area. The perimeter is the total distance around the outside, so the length plus the width plus the length plus the width, or more simply:



There are 3 feet in every yard.

John

My calculator said it, I believe it, that settles it
The Out Campaign: Scarlet Letter of Atheism



Trigonometry-basics/584655: How do you verify identities? example: sin/1-cos+1-cos/sin=2csc
1 solutions

Answer 372833 by solver91311(16868) About Me  on 2012-03-08 23:28:50 (Show Source):
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Apply the LCD and add the two fractions:



Apply the Pythagorean Identity to the numerator:



Factor a 2 out of the numerator:



Eliminate the factor common to both numerator and denominator:



Sine is the reciprocal of Cosecant, so:



John

My calculator said it, I believe it, that settles it
The Out Campaign: Scarlet Letter of Atheism



Geometry_proofs/584659: How do you prove that a/b is the same as b/a? Thanks!
1 solutions

Answer 372831 by solver91311(16868) About Me  on 2012-03-08 23:03:59 (Show Source):
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You can't. In fact, you can easily prove that, in general,

Let and let , then

And, in fact, if and only if because 1 is the only real number equal to its own reciprocal.

John

My calculator said it, I believe it, that settles it
The Out Campaign: Scarlet Letter of Atheism



Complex_Numbers/584346: (-1+3i)divided by (1+i)
1 solutions

Answer 372769 by solver91311(16868) About Me  on 2012-03-08 16:13:17 (Show Source):
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Multiply the fraction by 1 in the form of the conjugate of the denominator divided by itself:



Use FOIL for the numerator and the fact that the product of a pair of binomial conjugates is the difference of two squares for the denominator. Don't forget that

John

My calculator said it, I believe it, that settles it
The Out Campaign: Scarlet Letter of Atheism



Numeric_Fractions/584363: i do not understand this problem at all and i dont understand what im suppose to do on it... can you please explain to me? the problem is: A brick is 1 7/8 in. high Mortar that is 3/8 in. thick is spread on each row of bricks. How many rows of bricks are needed to reach the top of a 7 1/2-ft doorway? Please try to respond to this for me by tomorrow... my homework is due tomorrow and I really want to be able to know how to do this. Thank you so much for taking your time.
1 solutions

Answer 372763 by solver91311(16868) About Me  on 2012-03-08 15:16:54 (Show Source):
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inches per row.

, so seven and a half feet is 90 inches.

How many times will inches fit into 90 inches? Divide 90 by 2.25.

This assumes you lay the first course with no mortar beneath it (very dumb idea) or there is no layer of mortar on top of the last row of bricks.

John

My calculator said it, I believe it, that settles it
The Out Campaign: Scarlet Letter of Atheism



Linear_Equations_And_Systems_Word_Problems/584362: how can i solve this 1.The sets P, Q and R are such that P ∩Q and P ∪Q ⊂R.
a.) Draw a Venn diagram showing the sets, P,Q and R

1 solutions

Answer 372759 by solver91311(16868) About Me  on 2012-03-08 15:08:23 (Show Source):
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Draw a rectangle. Draw two partially overlapping circles inside of the rectangle.

Label the rectangle R and label one of the circles P and the other Q. Then P ∩ Q is the region where the two circles overlap and P ∪ Q is the area that comprises both circles including the overlap area. Both of these regions are fully contained in the universe region, R.

John

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Rectangles/584349: a rectangle 15 cm wide has a perimeter of
cm. what is the length of the rectangle
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Answer 372756 by solver91311(16868) About Me  on 2012-03-08 15:02:47 (Show Source):
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So divide your perimeter by 2 and subtract the width.

John

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Functions/584355: f=(-4y-7) find f=(y+h)
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Answer 372753 by solver91311(16868) About Me  on 2012-03-08 14:56:04 (Show Source):
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I think you mean:



Then



which you can simplify to



John

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Equations/584353: Find an equation of the line having given the slope and containing the given point. M=-6,(3,7) y=____
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Answer 372752 by solver91311(16868) About Me  on 2012-03-08 14:52:14 (Show Source):
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Use the point-slope form of an equation of a line:



where are the coordinates of the given point and is the given slope.

John

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Equations/584351: Is pair of lines parallel, perpendicular, or neither?
f(x)=-4x+7
g(x)=7x+3
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Answer 372750 by solver91311(16868) About Me  on 2012-03-08 14:50:51 (Show Source):
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Both are in slope-intercept form so that you can determine the slope of each by inspection. If the slopes are equal, the graphs are parallel (or possibly coincident). If the slopes are negative reciprocals, then the graphs are perpendicular. Otherwise, neither.

John

My calculator said it, I believe it, that settles it
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Probability-and-statistics/584299: Someone flips 15 biased coins once. The coins are weighted such that the probability of a head with any coin is 0.85.
(a) What is the probability of getting exactly 14 heads?

(b) What is the probability of getting at least 14 heads?

(c) What is the probability of getting exactly 3 tails?

Would I use the equation p= n!/(r!)(n-r)* p^r q^n - r
1 solutions

Answer 372742 by solver91311(16868) About Me  on 2012-03-08 13:36:09 (Show Source):
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Yep:

The probability of successes in trials where is the probability of success on any given trial is given by:



Where is the number of combinations of things taken at a time and is calculated by

For part (a) you want:



Calculation Hint:

For part (b) you want the probability of exactly 15 plus the result of part (a):




Calculation Hint: and , hence:



Part (c) is just straightforward fill in the numbers, get out the calculator, and crunch noting that the probability of a tail is 1 minus the probability of a head (save for that very, very tiny probability that the coin lands on its edge):



On the other hand you can save yourself a boatload of arithmetic drugery if you open up a spreadsheet (Excel under Windows or Numbers on a Mac, they both work the same), pick a convenient empty cell, and type in:

Part (a)

=BINOMDIST(14,15,0.85,false)

Part (b)

=BINOMDIST(14,15,0.85,false) + BINOMDIST(15,15,0.85,false)

Alternatively you could enter:

=1 - BINOMDIST(13,15,0.85,true)

Part (c)

=BINOMDIST(3,15,0.15,false)

John

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Graphs/584293: what does the graph for -2x + 3y = 1 look like?
1 solutions

Answer 372740 by solver91311(16868) About Me  on 2012-03-08 13:03:40 (Show Source):
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It is a straight line with a slope of that intersects the -axis at .

John

My calculator said it, I believe it, that settles it
The Out Campaign: Scarlet Letter of Atheism