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drk answered: 1901 problems
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1 solutions
Answer 189597 by drk(1908) on 2010-01-17 15:07:39 (Show Source):
You can put this solution on YOUR website!There appear to be 13 ways. Here they are in {p,n,d,q} form:
{p,n,d,q}
{0,0,0,1}
(0,1,2,0}
{5,0,2,0}
{0,3,1,0}
{5,2,1,0}
{10,1,1,0}
{15,0,1,0}
{0,5,0,0}
{5,4,0,0}
{10,3,0,0}
{15,2,0,0}
{20,1,0,0}
{25,0,0,0}
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Linear-equations/257732: how do I solve k(x)=x+20
k (o)=
k(-17)=
k (-12)=
k(14)=
K (d+17)= 1 solutions
Answer 189595 by drk(1908) on 2010-01-17 15:00:45 (Show Source):
You can put this solution on YOUR website!To solve these, use the phrase "letter goes away and number comes to stay as follows:
k(x)=x+20
k(0) = 0 + 20 = 20
k(-17) = -17 + 20 = 3
k (-12) = -12 + 20 = 8
k(14) = 14 + 20 = 34
K (d+17) = (d+17) + 20 = d + 37
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Geometry_proofs/257494: Given: Triangle ABC
Prove: m<4= m<1 + m<2
Picture: A triangle with line, CD, connected to it. A is m<1, B is m<2, C is m<3, and m<4 are vertical angles to m<3 1 solutions
Answer 189420 by drk(1908) on 2010-01-16 13:33:29 (Show Source):
You can put this solution on YOUR website!This is also called the exterior triangle theorem. With angle 4 vertical to angle 3, you cannot prove
angle 4 = angle 1 + angle 2. For this to work, angle 4 must be supplementary to angle 3. Here is the proof for that.
STATEMENT 1: triangle ABC
REASON 1: given
STATEMENT 2: angle 1 + angle 2 + angle 3 = 180 degrees
REASON 2: definition of sum of angles of triangle
STATEMENT 3: angle 3 + angle 4 = 180
REASON 3: definition of supplementary angles
STATEMENT 4: angle 1 + angle 2 + angle 3 = angle 3 + angle 4
REASON 4: substitution [2,3]
STATEMENT 5: angle 1 + angle 2 = angle 4
REASON 5: subtraction property of equality
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real-numbers/257495: Which set of numbers is not closed under multiplication? odd integers, even integers, prime numbers, or rational numbers. 1 solutions
Answer 189417 by drk(1908) on 2010-01-16 13:21:29 (Show Source):
You can put this solution on YOUR website!Primes are not closed under multiplication.
--
Look at each separately:
odd integers: odd x odd = odd [closed]
even integers: even x even = even [closed]
prime numbers: prime x prime = composite [NOT closed]
rational numbers: fraction x fraction = fraction [closed]
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Geometry_proofs/257490: Given: AB and CD bisects each other at M
Prove: AD is parallel to BC
Picture: Two triangles connecting to get, kind of like a bow tie. 1 solutions
Answer 189415 by drk(1908) on 2010-01-16 13:14:27 (Show Source):
You can put this solution on YOUR website!STATEMENT 1: AB bisects CD at M
REASON 1:given
STATEMENT 2: AM congruent BM
REASON 2: definition of bisector
STATEMENT 3: CM congruent DM
REASON 3: definition of bisector
STATEMENT 4: angle CMB congruent angle AMD
REASON 4: definition of vertical angles
STATEMENT 5:triangle CMB congruent triangle AMD
REASON 5: SAS
STATEMENT 6: CB congruent AD
REASON 6: CPCTC
STATEMENT 7: angle CBM congruent angle DAM
REASON 7: CPCTC
STATEMENT 8: CB is parallel to AD
REASON 8: definition of parallel lines.
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Rectangles/257489: you have 80 feet of fencing to enclose a rectangular region. what is the maximum area? 1 solutions
Answer 189413 by drk(1908) on 2010-01-16 13:09:36 (Show Source):
You can put this solution on YOUR website!The perimeter is
P = 2L + 2W or
80 = 2L + 2W
dividing by 2 we get
(i) 40 = L + W
THe area is
(ii) A = LW
solving (i) for L, we get
(iii) L = 40-W
substituting that in (ii), we get
(iv) A = (40-W)(W)
using completing the square, we get
A = -(W-20)^2 + 400
So, when W = 20, the max area is 400.
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Percentage-and-ratio-word-problems/257474: Amy paid $57.16 for a pair of shoes during a 35% off sale. What was the regular price? I am thinking that the original price was $163.14 but not sure if I am right. 1 solutions
Answer 189408 by drk(1908) on 2010-01-16 12:55:16 (Show Source):
You can put this solution on YOUR website!If reduce a price by 35%, you still have 65% left.
So,
.65P = 57.16
dividing we get
p ~ $87.94.
--
checking,
87.94*.35 ~ 30.78
87.94 - 30.78 ~ 57.16.
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Proportions/257482: the antecedent and consequent of a ratio differ by 40 and is equal to 2/7. find the ratio. 1 solutions
Answer 189407 by drk(1908) on 2010-01-16 12:52:07 (Show Source):
You can put this solution on YOUR website!We have a fraction of the following type
N/D, where D NOT = 0.
Based on the given information,
D - N = 40
and
N/D = 2/7.
This is a reduced number.
D = 40 + N
by substitution, we get
N / (40+N) = 2/7
cross multiply to get
7N = 80 + 2N
solve for N to get
5N = 80
N = 16
Since N = 16, D = 56
Our fraction is 16/56.
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Proportions/257485: if a number of two digits is divided by th number obtained after reversing the digits, we get 2.08 , if the sum of the digit is 7, find the number. 1 solutions
Answer 189406 by drk(1908) on 2010-01-16 12:47:38 (Show Source):
You can put this solution on YOUR website!Let the original number be expressed as

When you reverse the digits, you get

Now the quotient = 2.08 as

We also know that t + u = 7, so t = 7-u. We get

This gives us

cross multiplying, we get

solving for u, we get

original number is 52
reversed number is 25.
quotient is 2.08
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Graphs/257483: I did this linear equation problem, but I want to make sure it is right.
Graph a line using the "friendly numbers" -2, -1, 0, 1, 2
1. y = 2x + 3 This is the answer I put down:
x / 2x+3 / y / (x,y)
-2 / 2(-2)+3 / -1 / (-2,-1)
-1 / 2(-1)+3 / 1 / (-1,1)
0 / 2(0)+3 / 3 / (0,3)
1 / 2(1)+3 / 5 / (1,5)
2 / 2(2)+3 / 7 / (2,7)
I didn't know how to make columns on the computer for my answers. The
above should be in columns, but I put slashes to indicate the columns. Now I am thinking about the answer because it states to a graph a line using the friendly numbers. Are my columns enough or do I have to graph a line? 1 solutions
Answer 189405 by drk(1908) on 2010-01-16 12:40:23 (Show Source):
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Equations/257415: a motorist drove a for 2 hours at one speed & then for 3 hours at another speed & one hour at the second speed, he would have covered 2444km. find the two speeds. 1 solutions
Answer 189403 by drk(1908) on 2010-01-16 12:28:03 (Show Source):
You can put this solution on YOUR website!This is an RTD problem. Here is a table base on given information:
motorist . . . . . . . . .rate . . . . . . . . . .time . . . . . . . . . .distance
. . . . . . . . . . . . . . .. R1 . . . . . . . . . . . .2 . . . . . . . . . .. . 2R1
. . . . . . . . . . . . . . . .R2 . . . . . . . . . . . .3 . . . . . . . . .. . .3R2
. . . . . . . . . . . . . . . R2 . . . . . . . . .. . . . 1 . . . . . . . . .. . .1R2
. . . . . .. . . . . . . . . . .. .. . . . . . . . . . .6 . . . . . .. . . . . . .2444
We see that
(i) 
or dividing by 2, we get
(ii) 
and that the average rate is
avgR = 2444/6 = 407.33
This means that
(iii) 
or
(iv) 
substituting (iv) into (ii) we get
(v) 
(vii) 
solving for R2, we get

This makes R1

--
The rates appear to be the same.
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Triangles/257424: The equal sides of an isosceles triangle have lengths of (5x – 30) and (3x + 10).
What is the greatest possible integer value of the third side? 1 solutions
Answer 189398 by drk(1908) on 2010-01-16 12:10:22 (Show Source):
You can put this solution on YOUR website!We set the two sides equal to each other as
5x – 30 = 3x + 10
Solving for x, we get

Now, each side is worth 70.
We have a 70, 70, and x sided triangle.
Using the triangle inequality theorem, we get
70-70 < x < 70+70
or
0 < x < 140.
The greatest integer < 140 is 139.
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Human-and-algebraic-language/257470: A math test has a bonus question. The directions simply state that if you answer the question correctly you will recieve 5 bonus points and your test grade will be increased by 7% of your score. Let x = test score before answering the bonus question.
a) write a function, f(x) to represent just the 5 bonus points
b) Write a function, g(X) to represent just the precent of increase.
c) Explain the meaning of f(g(x))
d) Explain the meaning of g(f(x))
e) Does f(g(x)) = g(f(x)) in the problem? Explain
**** Please help me answer all these questions, i really dont understand. Please and thank you! 1 solutions
Answer 189393 by drk(1908) on 2010-01-16 12:03:55 (Show Source):
You can put this solution on YOUR website!X is the number of points.
First we have a proportion
5/N = 7/100
Solving, we get n ~ 71.42 or ~ 71.
There are 71 points on this test.
a) write a function, f(x) to represent just the 5 bonus points
ANSWER:

b) Write a function, g(x) to represent just the precent of increase.
ANSWER:

c) Explain the meaning of f(g(x))
ANSWER: The g(x) is a percentage which you then add to a number of points.
d) Explain the meaning of g(f(x))
ANSWER: f(x) is a raw score that you are converting into percentage
e) Does f(g(x)) = g(f(x)) in the problem? Explain
They are not the same.
f(g(x)) = (100x+855)/71
g(f(x)) = (100x + 1000)/71
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Permutations/257467: Find the probability that the sum of the values of two dice in a throw of two fair dice is 8, given that the one die is 5. 1 solutions
Answer 189388 by drk(1908) on 2010-01-16 11:28:34 (Show Source):
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Permutations/257468: An urn contains 3 white balls and 5 red balls. Two balls are drawn at random. If the first is replaced before the second is drawn, what is the probability that the first ball is white and the second is red? 1 solutions
Answer 189387 by drk(1908) on 2010-01-16 11:27:04 (Show Source):
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Permutations/257469: Five cards are dealt at random from a regular deck of 52 playing cards. Find the probability that three are sevens. 1 solutions
Answer 189386 by drk(1908) on 2010-01-16 11:25:39 (Show Source):
You can put this solution on YOUR website!This is a combination problem. We want 3 of the 4 sevens and don't care about the other cards. SO, we have
p(3 sevens) = (4c3)*(48c2) / (52c5) ~ 0.001736
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Average/257427: After ten tests, Bryan’s average test grade was 84. His teacher decided to drop each student’s lowest and highest test grade. This brought Bryan’s average up to 85. If his lowest test score (of the original 10 tests) was 24 points lower than his highest test, what was his highest test grade? 1 solutions
Answer 189385 by drk(1908) on 2010-01-16 11:23:04 (Show Source):
You can put this solution on YOUR website!So, we know that the average of 10 tests is 84. This is a total of 840 points.
We know the average of 8 tests is 85. his is a total of 680 points.
Let the highest score = H and the lowest score = H - 24.
--
8 tests + 2 dropped tests = 10 tests. SO, we get
680 + 2H - 24 = 840.
solving for H, we get
2H = 840 - 680 +24
2H = 184
H = 92
H-24 = 68
HIs highest grade was 92.
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Angles/257432: if a and b are complementary angles and a is 10 degrees greater than b, what size is angle b? 1 solutions
Answer 189383 by drk(1908) on 2010-01-16 11:17:54 (Show Source):
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Geometry_Word_Problems/257435: A cone sits on top of a cylinder. Both have a radius of 3. The heights of the
cylinder and cone are 8 and 4 respectively. Determine the exact volume of the
combined solid. 1 solutions
Answer 189382 by drk(1908) on 2010-01-16 11:16:17 (Show Source):
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Proportions/257438: Determine the value of n so that the roots of nx^2 – 8x + 10 = 0 are equal. 1 solutions
Answer 189381 by drk(1908) on 2010-01-16 11:13:08 (Show Source):
You can put this solution on YOUR website!Here is our equation
(i) nx^2 – 8x + 10 = 0
We need the discriminant part of the quadratic which is
(ii) 
From (i), the D is
(iii) 
We want The roots to be equal, so D = 0.
From (iii) we get
(iv) 
Solving for n, we get
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Miscellaneous_Word_Problems/257445: Snow White and the Seven Dwarfs went to work as carpenters. Each dwarf earned $20.
Snow White earned $3.50 more than the average of the eight. How much did Snow White earn? 1 solutions
Answer 189378 by drk(1908) on 2010-01-16 10:59:55 (Show Source):
You can put this solution on YOUR website!We can write an equation based on the given information. Let S = snow white. The 7 dwarfs + snow white = 8 people.

multiply all by 8 to get

subtract S and combine like terms to get

diving, we get
S = $24
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Permutations/257465: . A single card is drawn at random from a deck of 52 cards. Jack, Queen, and King are considered the only picture cards. Find the probability that the card will be a picture card. 1 solutions
Answer 189373 by drk(1908) on 2010-01-16 10:45:55 (Show Source):
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