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# Recent problems solved by 'JBarnum'

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 Linear-systems/569696: 28:39 What is the x-coordinate of this solution? 2x+3y=-27 -3x+2y=23 My Work is Shown Below: 3(2x-3y=-27) -3+2y=23 __________ 6x-9y=81 -3x+2y=23 _________ -18x-7y=104 +18 +18 -7y=122 __ ___ -7 -7 y= -17.42 ________________________________________________________________________________ Is that correct?1 solutions Answer 367429 by JBarnum(2044)   on 2012-02-08 14:29:23 (Show Source): You can put this solution on YOUR website!i have no idea what you were trying to do and no its not correct. easiest way is to do the elimination method but you could do substitution method if you wanted to first find the lowest common variable for y spot in both equations that will be easy to eliminate we want to eliminate the y so we can solve for the x coordinate best would be 2(2x+3y=-27) 3(-3x+2y=23) . now subtract the 2 equations . divide by 13
 Probability-and-statistics/569692: another friends ask you to explain how to tell if two events are dependent or independent ? how would you reply?1 solutions Answer 367424 by JBarnum(2044)   on 2012-02-08 13:52:40 (Show Source): You can put this solution on YOUR website!Dependent and Independent Events The occurrence of some events may affect the probability of occurrence of others. For example, the complementary events A and A cannot occur simultaneously. If one took place the other is out of the game: P(A|A) = 0 regardless of the probability P(A). (P(A|B) denotes the conditional probability of A assuming B.) We say that the event A is not independent of the event A (assuming P(A) ≠ 0 of couse.) And, in general, an event A is not independent of an event B iff P(A) ≠ P(A|B), i.e., if occurrence of B affects the probability of A. It may not be obvious right away, but the relationship "not independent" is symmetric: if A is not independent of B then also B is not independent of A. Formally, if P(A) ≠ P(A|B) then P(B) ≠ P(B|A). To see why that is so we invoke the defintion of conditional probability, P(A|B) = P(A∩B) / P(B), so that P(A) = P(A|B) implies P(A∩B) / P(B) = P(A), or P(A∩B) = P(A) P(B), which also may serve as the definition of independency of A from B. But the later relationship is symmetric! It implies P(B) = P(A∩B)/P(A) = P(B|A), which exactly means that B is independent of A. We see that two events A and B are either both dependent or independent one from the other. The symmetric definition of independency is this (*) P(A∩B) = P(A) P(B). Two events A and B are independent iff that condition holds. They are dependent otherwise. It's a frequent misconception that the independency or dependency of two events relates to their having or not having an empty intersection. The case of A and its complement A supplies a clear example of two dependent events with empty intersection. Another example was introduced in the discussion of conditional probabilities, where we considered the sets Ω = {1, 2, 3, 4, 5, 6, 7, 8}, A = {1, 3, 5, 7}, B = {7, 8}, A+ = {1, 2, 3, 5, 7} and A- = {3, 5, 7}. We found that P(B) = 1/4 whilst P(B|A+) = 1/5, P(B|A) = 1/4, P(B|A-) = 1/3. What this says is that B and A are independent whereas B is dependent on both A+ and A-. (Note that B∩A+ = B∩A = B∩A- = {7}.) Returning to the question of survival and life expectancy, AN is the event of a new-born reaching the age of N years. By the meaning of it, for N > M, AN⊂AM and therefore AN∩AM = AN. In particular this means that P(AN∩AM) = P(AN) so that P(AN∩AM) = P(AN)·P(AM) is equivalent to P(AN) = P(AN)·P(AM) which is only possible if P(AN) = 0 or P(AM) = 1. Since the latter is unrealistic and the former is unlikely for a reasonable age N, the two events AN and AM can't be independent. In fact, the probability of reaching a certain age grows with aging. As the time goes by, the size of the surviving population goes down while the number of person in a certain (advanced) age group is fixed. Thus the probability (which is the ratio of the two quantities) of getting into that group is indeed increasing with age. in reference to: http://www.cut-the-knot.org/Probability/IndependentEvents.shtml
 Word_Problems_With_Coins/569691: if you had a jar that contains 60 half dollars and 200 quarters what is the monetary value of the coins?1 solutions Answer 367423 by JBarnum(2044)   on 2012-02-08 13:48:19 (Show Source): You can put this solution on YOUR website!60/2=30 dollars 200/4=50 dollars 50+30=80 dollars worth
 Graphs/569689: x=10 How do you come up with answer 10 for x?1 solutions Answer 367422 by JBarnum(2044)   on 2012-02-08 13:44:26 (Show Source): You can put this solution on YOUR website! x doesnot equal 10 to prove it put 10 in place of x and solve . incorrect . correct
 Permutations/569688: can you help me with a + 4 < 10 what is a1 solutions Answer 367420 by JBarnum(2044)   on 2012-02-08 13:39:00 (Show Source): You can put this solution on YOUR website! SUBTRACT 4 from bothe sides 10-4=6
 Numbers_Word_Problems/569685: the sum of two numbers in 10. the first number is 2/3 of the second number. what are the numbers1 solutions Answer 367419 by JBarnum(2044)   on 2012-02-08 13:32:10 (Show Source): You can put this solution on YOUR website!F=first number S=second number
 Rectangles/569661: ?what is x?1 solutions Answer 367413 by JBarnum(2044)   on 2012-02-08 12:35:06 (Show Source): You can put this solution on YOUR website! find common denom fastest is to just multiply the two denoms 20*16=320 16*7=112 20*3=60 add reduce by 4 172/4=43 320/4=80
 Equations/569640: can you show the solution please?1 solutions Answer 367410 by JBarnum(2044)   on 2012-02-08 12:15:14 (Show Source): You can put this solution on YOUR website!i dont like fractions so first thing i do is multiply the denominators together 7y * 3 * 5 = 105y now multiply everything by 105y add 35y to both sides divide by 56 reduce by 2
 test/569642: 3 over x+4 minus 7 = -4 over x+ 41 solutions Answer 367405 by JBarnum(2044)   on 2012-02-08 12:02:07 (Show Source): You can put this solution on YOUR website!so simply multiply every thing by (x+4)
 Travel_Word_Problems/569638: Speed limit is 55 miles. How many kilometers can they travel?1 solutions Answer 367403 by JBarnum(2044)   on 2012-02-08 11:57:19 (Show Source): You can put this solution on YOUR website!incomplete question u have a speed limit and asking distance? according to your question the way its written its infinite kilometers. , are you trying to find out the same speed limit in kilometers? speed btw requires some type of time variable seconds minuts hours... if the speed limit is 55mph and you need to find the same speed limit in kph use the converson 1mile=1.609344kph or use a converson calculator 55mph=88.51392kph or paper pencil way with 55*1.609344kph=88.51392kph
 expressions/569625: 3x/5 -6=x1 solutions Answer 367402 by JBarnum(2044)   on 2012-02-08 11:47:35 (Show Source):
 Equations/569626: The length of the top of a computer is 2 1/5 feet longer than its width. If its width measures m feet, express its length as an algebraic expression in m.1 solutions Answer 367399 by JBarnum(2044)   on 2012-02-08 11:27:22 (Show Source): You can put this solution on YOUR website! if then
 Functions/569622: how do i graph constant function of f(x)=2 and use the graph to identify domain and range of f 1 solutions Answer 367397 by JBarnum(2044)   on 2012-02-08 11:23:09 (Show Source): You can put this solution on YOUR website!y is always at 2 so no matter what x you have y will stay at 2 1,2 2,2 3,2 4,2 its a horizontal line at (0,2) domain is what the x's are and range is what the y's are y is always 2 so the range = {2} x can be any numer negative or possitive so domain ={-infinity,infinity}
 Linear-equations/569621: x-9=-6x+51 solutions Answer 367396 by JBarnum(2044)   on 2012-02-08 11:14:00 (Show Source): You can put this solution on YOUR website!ADD 6X to both sides ADD 9 to both sides DIVIDE by 7
 Numeric_Fractions/569604: WHAT IS 6/9 TIMES 3/141 solutions Answer 367395 by JBarnum(2044)   on 2012-02-08 11:01:47 (Show Source): You can put this solution on YOUR website!or simply cross cancel
 test/569586: 3x over 5 minus x-3 over 2 = x+2 over 3. The answer is not a whole number answer. 1 solutions Answer 367390 by JBarnum(2044)   on 2012-02-08 10:40:45 (Show Source): You can put this solution on YOUR website! multiply denominators together 5*3*2=30 then multiply everything by that number add like terms subtract 20 and 3x from both sides divide by 7
 test/569587: 1 solutions Answer 367377 by JBarnum(2044)   on 2012-02-08 09:44:47 (Show Source):
 test/569588: wat does a dot look like?1 solutions Answer 367376 by JBarnum(2044)   on 2012-02-08 09:42:07 (Show Source):
 test/569589: 1 solutions Answer 367375 by JBarnum(2044)   on 2012-02-08 09:41:15 (Show Source):
 Miscellaneous_Word_Problems/569580: Emma is making a model of a Mardi Gras float. She is making it from a shoebox that measures 10 in. wide x 6in. long x 5in. high. She will cover the bottom and all four sides with velvet. How many square in. of velvet will she need?1 solutions Answer 367374 by JBarnum(2044)   on 2012-02-08 09:40:21 (Show Source): You can put this solution on YOUR website!this is a perimeter problem minus 1 top side, total(t) square inches the top and bottom are l*w the two long sides are h*l the two short sides are h*w since theres only the bottom we dont multiply by 2 for the lw sides
 Linear_Equations_And_Systems_Word_Problems/569581: Denise is selling roses. She sold 3 for \$5 and 5 for \$7. What will Denise charge for 12 roses if she keeps selling roses at the same rate ?1 solutions Answer 367373 by JBarnum(2044)   on 2012-02-08 09:27:54 (Show Source): You can put this solution on YOUR website!7/9 , 9/11 , 11/13 , 13/15 so we know its between 13 and 15 dollars it makes since that its adding a dollar more per rose 3 for 5 4 for 6 5 for 7 6 for 8 7for 9 so 11 for 13 , 12 for 14 , 13 for 15 12 for 14 dollars
 test/569582: The difference of fifty and fifteen less than a number1 solutions Answer 367372 by JBarnum(2044)   on 2012-02-08 09:20:14 (Show Source):
 Inequalities/569577: To pass a course, corrina needs an average score of 60 or more. If Corina 's scores are 66 72 90 49 and 59 find the minimum score that maria can get on her sixth and last exam and pass the sourse.1 solutions Answer 367370 by JBarnum(2044)   on 2012-02-08 09:17:55 (Show Source):
Quadratic_Equations/569574: Find Y in the following equation:

1 solutions

Answer 367367 by JBarnum(2044)   on 2012-02-08 08:59:59 (Show Source):
You can put this solution on YOUR website!

 Solved by pluggable solver: SOLVE quadratic equation with variable Quadratic equation (in our case ) has the following solutons: For these solutions to exist, the discriminant should not be a negative number. First, we need to compute the discriminant : . Discriminant d=56 is greater than zero. That means that there are two solutions: . Quadratic expression can be factored: Again, the answer is: 3.87082869338697, 0.129171306613029. Here's your graph:

 Miscellaneous_Word_Problems/569569: James derew a rectangle that was 10in. wide and 14 in. long. Inside the rectangle he drew a triangle. What is the area of the largest triangle he could draw inside the rectangle?1 solutions Answer 367366 by JBarnum(2044)   on 2012-02-08 08:53:05 (Show Source): You can put this solution on YOUR website!uh the largest triangle would be exactly half of the area of the rectangle by drawing the diagnal creating 2 90 degree triangles fastest way is find area of rectangle and divide by 2 140/2=70
 Money_Word_Problems/569557: I loaned a friend \$6,000.00 she said she would pay me 6% interest. She is paying me back at the rate of \$50.00 a month. How long will it take for her to pay me back the principal and interest. 1 solutions Answer 367363 by JBarnum(2044)   on 2012-02-08 08:43:49 (Show Source): You can put this solution on YOUR website!well is the interest per month or year also is it compound interest or simple interest...without these variables its not possible to get the correct answer unless you want 4 answers to the question. please make sure the question has its specifics or its an incomplete question or ask for all 4 possibilities. 6%of 60000= 360 meaning total of 6360 so if its 6% a month its something like pay the 50 first month 6360-50=6310 *.06=6688.6 6688.6-50=6638.6 shed never pay it off so i doubt this method say just simple interes of 6% no per month or year. 6%of 60000= 360 meaning total of 6360 6360/50=127.2 months .2*30=6 days 127/12=10.58 10years 7months 6days the principle is simple 50*12months=600, 600*10years=6000, so 10 years for simple interest payback of the principle. another 7months and 6 days for the simple interest...idont know if this is the answer you arelooking for but good luck either way i wouldnt lend someone 6 grand if they only paying me back 50 bucks a month or id charge compound interest atleast because of how long it takes them to pay it back but its just a question.
 Square-cubic-other-roots/569554: Show work so that I can see how you get the answer1 solutions Answer 367359 by JBarnum(2044)   on 2012-02-08 08:15:35 (Show Source): You can put this solution on YOUR website! look for squares squares shown then seperate below square root of a square canceles out add like terms
 Age_Word_Problems/569549: 5 years ago the sum of my age and my daughters age was a third of five times the average of the present ages of my daughter and my self if my daughter will be 15 years old in 5 years how old is tim now1 solutions Answer 367358 by JBarnum(2044)   on 2012-02-08 07:52:20 (Show Source): You can put this solution on YOUR website!m=my age d=daughter age im going to explain the above equation as its second nature for me but for some this may be hard to get this equation from words: 1) the is same as "5 years ago the sum of my age and my daughters age" and are the present ages so subtracting 5 years from each of them makes it 5 years ago 2) is same as "the average of the present ages of my daughter and my self" average is adding both ages and dividing them by the number of ages added 3) is same as "five times the average of the present ages of my daughter and my self" multiplying by 5 4) is same as "a third of five times the average of the present ages of my daughter and my self" multiplying by a third . . "my daughter will be 15 years old in 5years" so who is tim? dumb question we dont know who tim is and what tim's age is so its an incomplete question but if you wanted to find your age it is as follows. substitute for solve for add like terms and distribute the and multiply by and subtract from each side . check correct
 Average/559456: how can i find the average of 85% of 361 solutions Answer 363426 by JBarnum(2044)   on 2012-01-19 08:55:16 (Show Source): You can put this solution on YOUR website!there is no average theres only 1 definite solution = average is where u take a set of numbers and then divide by how many numbers there are to get average number.
 Functions/558998: Can you evalute this expression: g(√8) Given that f(x) = 2x+1/3-5x and g(y) = 1/√y²+1 ?1 solutions Answer 363290 by JBarnum(2044)   on 2012-01-18 14:56:03 (Show Source): You can put this solution on YOUR website!well the f(x) doesnt apply in this case