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Recent problems solved by 'sophxmai'
sophxmai answered: 60 problems
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Expressions-with-variables/619347: if it cost $78.86 to buy 3 tickets in japan plus 2 tickets in switzerlan. 3 tickets in switzerland plus 2 tickets in japan cost $74.84. how much does an average movie ticket cost in each country? 1 solutions
Answer 389562 by sophxmai(60) on 2012-06-09 23:45:45 (Show Source):
You can put this solution on YOUR website!x=Japan
y=Switzerland
3x+2y=78.86
2x+3y=74.84
Find x and y
Multiply each equation to cancel one of the variables out.
3x+2y=78.86 x2
6x+4y=157.72
2x+3y=74.84 x3
6x+9y=224.52
Now the two equations have 6x, and if you subtract one from the other, you can cancel out one of the variables.
6x+4y=157.72
6x+9y=224.52
-5y=-66.8
y=-66.8/-5
y=13.36
Now you have y, substitute y into an equation to find x.
2x+3y=74.84
2x+3(13.36)=74.84
2x+40.08=74.84
2x=34.76
x=34.76/2
x=17.38
So tickets in Japan cost $17.38 and tickets in Switzerland cost $13.36
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Probability-and-statistics/619296: If 11 coins are tossed what is the probability of getting EXACTLY 2 heads? 1 solutions
Answer 389561 by sophxmai(60) on 2012-06-09 23:37:06 (Show Source):
You can put this solution on YOUR website!If 11 coins are tossed what is the probability of getting EXACTLY 2 heads?
Use P(x=k)=nCk*p^k*q^(n-k)
Where p=probability of success and q=1-p, probability of failure
So
P(x=2)=(11C2)(1/2)^2(1/2)^(11-2)
=(11C2)(1/4)(1/512)
=(11C2)(1/2048)
=0.0269
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Probability-and-statistics/619298: A 5-card hand is dealt from a deck of 52 cards. What is the probability that
a.) none are queens?
b.) all are queens? 1 solutions
Answer 389560 by sophxmai(60) on 2012-06-09 23:31:28 (Show Source):
You can put this solution on YOUR website!There are only 4 queens in a deck of cards.
P(a)= probability that event A occurs
= (total number of desired outcomes)/(total number of possible outcomes)
Use combinatorics.
The total number of possible outcomes in a) and b) is
52C5 = 2598960
The total number of desired outcomes in a) is
48C5 = 1712304
It's 48 because you don't want any queens, and there are 4 queens in a deck of 52
The total number of desired outcomes in b) is
0 because there are only 4 queens in a deck of 52, but you want your 5 card hand to be all queens.
So
a)P(no queens in a 5 card hand)=1712304/2598960=0.659
b)P(all queens in a 5 card hand)=0/2598960=0
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Probability-and-statistics/619301: A 5-card hand is dealt from a deck of 52 cards. What is the probability that exactly one card is a king? 1 solutions
Answer 389558 by sophxmai(60) on 2012-06-09 23:03:43 (Show Source):
You can put this solution on YOUR website!Probability is (total number of desired outcomes)/(total number of possibly outcomes)
Desired outcome: you want 1 king, and 4 other cards
To get that, you use combinatorics:
4C1 x 48C4 = 778320
Total outcome: 5 card hand
To get that, you do 52C5 = 2598960
Then the probability is
P(1 king in a 5 card hand)= 778320 / 2598960 = 0.299
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Inequalities/614742: Graph the inequality. 2x-7y>14 Determine if the graph is solid or dotted, and shaded above or below: 1 solutions
Answer 386687 by sophxmai(60) on 2012-05-25 05:04:40 (Show Source):
You can put this solution on YOUR website!2x-7y>14
Determine if the graph is solid or dotted, and shaded above or below.
First off, the graph is dotted. You can tell this because the inequality sign is greater/less than. If the sign was greater/less than or equal to, then the graph would be a solid.
To determine whether the graph is shaded above or below, you must first solve for y, and graph it.
So the equation is 
To graph this, look at it with an equal sign instead. 
This has a y-intercept of -2, and a slope of 2/7.
Now to determine what part is shaded, look at the equation that is solved for y, and pay attention to the inequality sign. If it is y>... then it is shaded above. If it is y<... then it is shaded below. In this case, it is shaded below.
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Exponential-and-logarithmic-functions/614548: Solve for x: 1 solutions
Answer 386601 by sophxmai(60) on 2012-05-24 15:22:04 (Show Source):
You can put this solution on YOUR website!take the log of both sides and then separate the 2(3^x) by the log(m)+log(n)=log(mn) rule.
log(2(3^x))=log(7(5^x))
log(2)+log(3^x)=log(7)+log(5^x)
log(2)+xlog(3)=log(7)+xlog(5)
xlog(3)-xlog(5)=log(7)-log(2)
x(log(3)-log(5))=log(7)-log(2)
x=(log(7)-log(2))/(log(3)-log(5))
x=-2.452427 <--i used a calculator
x=(log(7)-log(2))/(log(3)-log(5)) can be rewritten using the rule log(m)-log(n)=log(m/n)
x=log(7/2)/log(3/5)
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Linear-systems/614544: 2x – 5y = -1
x – 3y = -3
1 solutions
Answer 386597 by sophxmai(60) on 2012-05-24 15:14:45 (Show Source):
You can put this solution on YOUR website!2x–5y=-1
x–3y=-3
You first want to get rid of one of the variables.
There are two different ways of doing this.
The first way is to solve the 2nd equation for x, and then plug it into the 1st equation to solve for y.
The second way is to multiply the 2nd equation by 2, and then subtract this new equation from the 1st equation so that x cancels out. Left with y, you solve for it.
The first way.
2x–5y=-1
x–3y=-3
Solve the 2nd equation for x
x-3y=-3
x=3y-3
Substitute x into the first equation
2x-5y=-1
2(3y-3)-5y=-1
Simplify and solve for y
2(3y-3)-5y=-1
6y-6-5y=-1
y=5
Plug y back into an equation with x in it.
x=3y-3
x=3(5)-3
x=15-3
x=12
The second way.
2x–5y=-1
x–3y=-3
Multiply the 2nd equation by 2
x–3y=-3
(x-3y=-3)x2
2x-6y=-6
Subtract the new equation from the first equation.
2x–5y=-1
2x-6y=-6
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y=5
Plug y into an equation with x in it.
x–3y=-3
x-3(5)=-3
x-15=-3
x=12
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Equations/614535: Find the choice below which gives a first step in solving the given system of equations by the addition method.
2x -3 y= 7
X-4y = 2
Do you; multiply the first equation by 3 and the second by 4
- multiply the first equation by -4 and the second by -2
-Multiply the second equation by 2
- Multiply the first equation by 4 1 solutions
Answer 386592 by sophxmai(60) on 2012-05-24 15:04:30 (Show Source):
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Miscellaneous_Word_Problems/609683: there are 340 tickets and three kids the mom wants to split them where james has 40 less than ashley and ashley gets 80 less than amanda how many tickets does each kid get 1 solutions
Answer 383898 by sophxmai(60) on 2012-05-10 18:33:24 (Show Source):
You can put this solution on YOUR website!Let:
x=James's tickets
y=Ashley's tickets
z=Amanda's tickets
Write your equations
x+y+z=340
x+40=y
y+80=z
Now solve your system...
x+40=y
x-y=-40
x+y+z= 340
x-y =-40
2y+z= 380
z= 380-2y
y+80=z
y+80=380-2y
y+2y=380-80
3y=300
y=100
z=380-2y
z=380-2(100)
z=380-200
z=180
x+40=y
x+40=100
x=60
Check:
x+y+z=340
60+100+180=340
James has 60 tickets.
Ashley has 100 tickets.
Amanda has 180 tickets.
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Rectangles/607684: The perimeter of a rectangle is 48 cm. The length is 6 cm less than twice the width. Which system would model this situation, and what are the length and the width? 1 solutions
Answer 382836 by sophxmai(60) on 2012-05-06 16:35:01 (Show Source):
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Numeric_Fractions/607279: can you show me how to divde 4 7/8 by 1/2? 1 solutions
Answer 382560 by sophxmai(60) on 2012-05-05 02:36:28 (Show Source):
You can put this solution on YOUR website!You want to divide 4 7/8 by 1/2
First make the 4 7/8 into an improper fraction
(4*8+7)/8=39/8
Now you have (39/8) divide by (1/2)
Flip the fraction after the divide sign and change the sign into a multiply sign
(39/8) x (2/1)
Now multiply them together
(39/8) x (2/1)
=(39/4)
If it says to make it into a proper fraction again, do so
39/4= 9 3/4
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Surface-area/607280: the perimeter of a college athletic field is 92 meters and the length is 12 m more than the width. find the length and width. 1 solutions
Answer 382559 by sophxmai(60) on 2012-05-05 02:32:56 (Show Source):
You can put this solution on YOUR website!the perimeter of a college athletic field is 92 meters and the length is 12 m more than the width. find the length and width.
Let x=length and y=width
2x+2y=92
x-12=y
Substitute the 2nd equation into the first one
2x+2y=92
2x+2(x-12)=92
2x+2x-24=92
4x=116
x=116/4
x=29
Substitute x into one of the original equations
x-12=y
29-12=y
17=y
the length is 29m, the width is 17m
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Age_Word_Problems/607031: The sum of the ages of a man and his wife is 80 years. 10 years ago, the ages of the wife was exactly two-third the age of the man. Find the present ages of the man and his wife. 1 solutions
Answer 382353 by sophxmai(60) on 2012-05-04 04:00:36 (Show Source):
You can put this solution on YOUR website!The sum of the ages of a man and his wife is 80 years. 10 years ago, the ages of the wife was exactly two-third the age of the man. Find the present ages of the man and his wife.
Let:
man's age = x
wife's age = y
x+y=80 <--sum of their age
y-10=2/3x <--10 years ago, the age of the woman was 2/3 of the man's current age
y=2/3x+10 <--solve the 2nd equation for y
x+2/3x+10=80 <--plug above into 1st equation
5/3x=70 <--simplify and solve
x=42 <--plug back into original equation to find y
42+y=80
y=80-42
y=38
Since x=42 and y=38
The man's age is 42 and the wife's age is 38
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Permutations/607044: 1 solutions
Answer 382352 by sophxmai(60) on 2012-05-04 03:52:53 (Show Source):
You can put this solution on YOUR website!From a group of eight boys amd two girls a boy and a girl will be selected to attend a conference.
In how many ways can the selection be made?
First choose your boy:
8C1
Then choose your girl:
2C1
Now multiply them together
8C1 x 2C1
So now you get 8x2 which = 16
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Age_Word_Problems/607061: please help me solve this problem.
Eva is 2 years older than Julienne. The sum of their ages is 20. Find their present ages. 1 solutions
Answer 382350 by sophxmai(60) on 2012-05-04 03:35:53 (Show Source):
You can put this solution on YOUR website!Eva is 2 years older than Julienne. The sum of their ages is 20. Find their present ages.
Let:
Eva's age = x
Julienne's age = y
x+y=20 <--the sum of their ages is 20
x-2=y <--Eva is 2 years older than Julienne
You can solve this system by either adding/subtracting or substituting.
Adding/Subtracting:
x+y=20
x-2=y
Rearrange the 2nd equation
x-2=y becomes x-y=2
So now we have
x+y=20
x-y=2
Now add the equations, you will get
2x=22
Now solve...
2x=22
x=11
Now that you have x, plug it into one of the equations to solve for y
x-y=2
11-y=2
11-2=y
9=y
Since x=11 and y=9
Eva's age is 11 and Julienne's age is 9
Substituting:
x+y=20
x-2=y
Since the 2nd equation is already arranged in a way that a variable = something... substitute it into the 1st equation.
x+y=20
x+(x-2)=20
x+x-2=20
2x-2=20
2x=22
x=11
Now that you have 11, plug x into your 2nd equation
x-2=y
11-2=y
9=y
Since x=11 and y=9
Eva's age is 11 and Julienne's age is 9
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Functions/379447: I need to evaluate the function at each specified value of the independent variable and simplify.
f(x) = the square root of (x+9) + 6 (the six is on the outside of the square root)
f(-9)
f(7)
f(x-9) 1 solutions
Answer 269381 by sophxmai(60) on 2010-12-01 22:22:41 (Show Source):
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Quadratic_Equations/379457: Wright a quadratic equation in the variable x having the given numbers as solutions. Type the equation in standard form, ax^2+bx+c=0
The solutions are -7,1
1 solutions
Answer 269379 by sophxmai(60) on 2010-12-01 22:16:42 (Show Source):
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Graphs/379389: how do you put the two ponits (5,-5) (0,8) into slope intersept form 1 solutions
Answer 269363 by sophxmai(60) on 2010-12-01 21:19:50 (Show Source):
You can put this solution on YOUR website!The points that are given to you are (5,-5) and (0,8).
The equation is y=mx+b.
What you need to find is the slope, m and the y-intercept, b.
To find the slope, m, you use the formula:
So,
Now from y=mx+b, we have 
To find the y-intercept, we can substitute one of the points in for x and y, and solve for b.
(0,8)
Now from y=mx+b, we have
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