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# Recent problems solved by 'richwmiller'

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 Complex_Numbers/252585: what is the answer to the complex number x=2-3i1 solutions Answer 184567 by richwmiller(9143)   on 2009-12-29 14:23:42 (Show Source): You can put this solution on YOUR website!Depends on what it is you want. Your question is similar to what is the answer to 2/3? x=2-3i is in standard format and is simplified as much as possible. We could plot it on the complex plane. Is that your question?
 Trigonometry-basics/252523: how do I go about solving sec(arcsin8/17)?1 solutions Answer 184494 by richwmiller(9143)   on 2009-12-29 04:25:23 (Show Source): You can put this solution on YOUR website!start inside the parentheses first let x= arcsin(8/17) remember if y=arcsin(x) then x=sin(y) after you solve for x then solve for sec(x)
 Probability-and-statistics/252525: 1+3+5+7+9+11+13+15+17+19=100 now pick any 5 digits which make the sum of 50 ?1 solutions Answer 184493 by richwmiller(9143)   on 2009-12-29 04:00:47 (Show Source): You can put this solution on YOUR website!this was answered yesterday since all are odd and 5 odds equal an odd it can't be done
 Linear_Algebra/252519: Can someone please point me in the right direction with this experiment. Probabilities and Binomial Experiments. U.S. Population by Region. The U.S. population by region (in millions) for selected years is given in the table. Find the probability that a U.S. resident selected at random satisfies the following: a.) lived in the West in 1997. b.) lived in the Midwest in 1995. c.) lived in the Northwest or Midwest in 1997. d.) lived in the South or West in 1997. e.) What are the odds that a randomly selected U.S. resident in 2000 was not from the South? REGION 1995 1997 2000 Northwest 51.4 51.6 53.6 Midwest 61.8 62.5 64.4 South 91.8 94.2 100.2 West 57.7 59.4 63.2 (Answers) a. .222 b. .235 c. .426 d. .574 e. 302 to 167 1 solutions Answer 184491 by richwmiller(9143)   on 2009-12-29 01:43:14 (Show Source): You can put this solution on YOUR website!the first thing to do is finish the table with totals for us population for each year in question REGION 1995 1997 2000 Northwest 51.4 51.6 53.6 Midwest 61.8 62.5 64.4 South 91.8 94.2 100.2 West 57.7 59.4 63.2 sum(1995)=51.4+61.8+91.8+57.7 sum(1997)=51.6+62.5+94.2+59.4=267.7 sum(2000)=53.6+64.4+100.2+63.2 a) lived in west in 1997 59.4/267.7=.2219=.222 so the part over the whole= probability
 Linear_Algebra/252520: Concept Check. If the probability of an event is .857, what is the probability that the event will not occur? (Answer) .143 1 solutions Answer 184489 by richwmiller(9143)   on 2009-12-29 01:16:49 (Show Source): You can put this solution on YOUR website!certainty =100%=1.00 1.00=.857 (yes) + n(no) 1.00-.857=.143= n
 Coordinate-system/252502: Solve the following system of equations algebraically: 2y = 8 − x y − 2x = −1 1 solutions Answer 184487 by richwmiller(9143)   on 2009-12-29 00:55:29 (Show Source): You can put this solution on YOUR website!put the two equations in the same order 2y=8-x y=2x-1 y=-1+2x (A) 2y=8-x (B) multiply (A) by 2 2y=-2+4x (C) 2y=8-x (B) 2y=2+4x (c) subtract C from B 0=6-3x subtract 6 from both sides 6=3x divide both sides by -3 2=x substitute 2 for x in any equation 2y=8-x 2y=8-(2) 2y=8-2 2y=6 y=3 x=2 check y=2x-1 3=2(2)-1 3=3 ok
 Numbers_Word_Problems/252512: when N is divided by 5, the remainder is 3. what is the remainder when 7N is divided by 5?1 solutions Answer 184485 by richwmiller(9143)   on 2009-12-29 00:41:00 (Show Source):
 Coordinate-system/252499: What is the solution for the following system of equations? x = -y x + 2y = 6 1 solutions Answer 184484 by richwmiller(9143)   on 2009-12-29 00:39:46 (Show Source): You can put this solution on YOUR website!substitute -y for x in the second equation -y+2y=6 y=6 x=-y substitute 6 for y x=-6
 Travel_Word_Problems/252514: What average acceleration does it take to stop a car traveling at 60 kph in 8 seconds1 solutions Answer 184483 by richwmiller(9143)   on 2009-12-29 00:37:14 (Show Source): You can put this solution on YOUR website!v=vinit+acceleration *time 0=60+acc*8 -60=acc*8 acc=-60/8 acc=-30/4 acc=-15/2 acc=-7.5 kps which of course is deceleration
 Equations/252518: (-6k^4)^21 solutions Answer 184477 by richwmiller(9143)   on 2009-12-29 00:18:59 (Show Source): You can put this solution on YOUR website!2^5=32 2^6=64 2^4=16 2^3=8 and 2^2=4 does (2^3)^2= 2^6 or 2^5? does 8^2=(2^3)^2=64? so a power raised to a power is multiplied so (-6k^4)^2=36k^8 yes, don't forget to square the -6 since it is within the parentheses
 Linear_Algebra/252517: Please help. I cannot figure just what formula to use. (Using Nonlinear Systems) Solving problems using a System of of Equation in two variables. Unknown numbers. Find two numbers whose sum is 10 and whose squares differ by 20. Answer( 6 and 4) 1 solutions Answer 184476 by richwmiller(9143)   on 2009-12-29 00:09:37 (Show Source): You can put this solution on YOUR website!there is no formula but we must make two equations with two unknowns let n and m be the two numbers n+m=10 n^2-m^2=20 n=10-m substitute (10-m)^2-m^2=20 100-20m+m^2-m^2=20 fortunately the squared variables are cancelled out 80-20m=0 80=20m 4=m n=10-m n=10-4=6
 Graphs/252516: How do i simplify and solve this equation 6-2x=5x-9x+101 solutions Answer 184475 by richwmiller(9143)   on 2009-12-29 00:03:38 (Show Source): You can put this solution on YOUR website!the goal is to get all numbers on one side and all letters (x in this case ) on the other. We do that by adding to both sides or subtracting from both sides or dividing both sides or multiplying both sides. but first we combine terms on each side. so we combine terms on the right side 5x-9x=-4x so now we have 6-2x=-4x+10 we want all numbers on the right and all letters on the left so what do we do to remove numbers from the left we subtract 6 because 6-6=0 so -2x=-4x+4 we want x on the left so we add 4x to both sides because -4x+4x=0 2x=4 divide by 2 x=2 now we check if the number on the right equals the number on the left then x does = 2 6-2x=5x-9x+10 6-2(2)=5*2-9*2+10 6-4=10-18+10 2=20-18 2=2 ok
 Graphs/250827: The directions: Write an equation in standard form for each line described. The Problem: The line that passes through (-1,3) and is parallel to 3x-y=41 solutions Answer 184463 by richwmiller(9143)   on 2009-12-28 20:29:17 (Show Source): You can put this solution on YOUR website!y=3x+6 is in slope intercept form standard form is ax+by=c 3x-y=-6
 Numeric_Fractions/252495: 2/3 x 1/4 x 3/5=1 solutions Answer 184461 by richwmiller(9143)   on 2009-12-28 20:19:56 (Show Source): You can put this solution on YOUR website! many cancel each other out the 3 of 2/3 cancels out the 3 of 3/5 the 2 of 2/3 is cancelled out by the 4 of 1/4 2/3*1/4=1/3*1/2 1/3*3/5=1/5 which leaves us with 1/5*1/2=1/10 2/3*1/4*3/5=1/5*1/2=1/10
 Unit_Conversion_Word_Problems/252494: If the dimensions of a cube of sample are 3 inches * 6 inches * 1 foot, what's the volume of that cube in cubic centimeters? Give your answer in scientific notation.1 solutions Answer 184460 by richwmiller(9143)   on 2009-12-28 20:03:33 (Show Source): You can put this solution on YOUR website!A cube has all sides equal. What are these dimensions you speak of? No. I didn't answer your question because your question makes no sense. You have three dimensions which are not equal and say that they are dimensions of a cube. That can't be because a cube has all sides equal A cube can't have height, width and length different. A cube has height, width and length that are all the same. So your question is messed up. You might as well ask me for the corners of a circle. They don't exist. And your cube is not a cube.
 Mixture_Word_Problems/252487: how much pure acid is in 800 gallons of a 38% acid soloution1 solutions Answer 184429 by richwmiller(9143)   on 2009-12-28 17:02:05 (Show Source): You can put this solution on YOUR website!38% of 800 is .38*800 38 is 2 less than 40 40% is .4=4/10 4/10*800=320 so 38% should be a little less than 320 2/100*800=16 320-16=304 304 gallons of acid in 800 gallons of 38%
 Geometry_proofs/252485: please i need help on proofs, i don't understand anything about it...thank you!!1 solutions Answer 184427 by richwmiller(9143)   on 2009-12-28 16:50:39 (Show Source): You can put this solution on YOUR website!proofs are logic and reasoning proofs start with what you know and reason to something you didn't know. we often start with definitions based on the information we know and the definition we can assume other info.sometimes it is better to start with the thing to be proven and work backwards.
 Finance/252477: Find the proceeds for the given amount repaid, time, and simple discount rate. \$42,000, discount rate 12%, 6 months. 1 solutions Answer 184407 by richwmiller(9143)   on 2009-12-28 14:40:46 (Show Source): You can put this solution on YOUR website!I=prt i=42000*12*1/2=2520
 Surface-area/252471: How do You find the area of an equilateral triangle with a radius of 2 radical 3? All I know is that the area formula is s^2 radical 3/ 41 solutions Answer 184399 by richwmiller(9143)   on 2009-12-28 14:08:31 (Show Source): You can put this solution on YOUR website!check out this problem where it has 6 you should put 2sqrt(3) http://en.allexperts.com/q/Geometry-2060/area-equilateral-triangle-given.htm
 Rate-of-work-word-problems/252467: First I just hope I'm in the right section, I have been trying to figure out how to solve this problem but I just can't come up with the right formula. An office has an old copying machine and a new one. Working together it takes both machines 6 hours to make all the copies of the annual financial report. Working alone the old machine takes 15 hours longer than the new machine. How long would it take the new machine to make all the copies working alone?1 solutions Answer 184395 by richwmiller(9143)   on 2009-12-28 13:58:09 (Show Source): You can put this solution on YOUR website!I moved the problem to word problems rate of work. What do we know? old machine takes x+15 in one hour old machine takes 1/(x+15) new machine takes x hours in one hour the new machine takes 1/(x) o=6 and n=6 together they take 6 hours n/x+o/(x+15)=1 6/x+6/(x+15)=1 x=8.10= new machine alone x+15=23.1 old machine alone
 Money_Word_Problems/252466: Jim is able to sell a hand carved statue for \$670 which was a 35% profit over his cost. How much did the statue originally cost?1 solutions Answer 184381 by richwmiller(9143)   on 2009-12-28 12:52:25 (Show Source): You can put this solution on YOUR website!1.35x=670 =cost plus profit x=496.30 original cost
 Geometry_Word_Problems/252465: the height of a over sized container is 3m. Its diameter is 2m.What is its area?(A)16m2(B)12m2 (C)18m2 (D)25m21 solutions Answer 184379 by richwmiller(9143)   on 2009-12-28 12:41:18 (Show Source): You can put this solution on YOUR website!Assuming this a cylindrical container, we can calculate the area. radius =1 meter 2*pi*r*h=surface area without ends =2*3.14*1*3=18.84 m^2 2*pi*r*h+2*(pi*r*r) 2*3.14*1*3+2*3.14*1*1 (2*3.14*1)*(3+1)=25.12m^2
 Geometry_Word_Problems/252464: The center of the compass should be placed on (a)the edge of the ray (B)the line (C)at the end of the ray (D)the vertex of the angle1 solutions Answer 184377 by richwmiller(9143)   on 2009-12-28 12:31:08 (Show Source): You can put this solution on YOUR website!Depends on what you are trying to do! How about a hint?
 Geometry_Word_Problems/252463: use the slope formula to find the slope of a line at (-3,0)and (4,3). Is it (A)1/3 or (B)-1/3 or (C)7/3 or (D)3/71 solutions Answer 184376 by richwmiller(9143)   on 2009-12-28 12:29:55 (Show Source): You can put this solution on YOUR website!slope (m) is the difference in rise (y) over the difference in run(x) (y1-y2)/(x1-x2)=m (0-3)/(-3-4)=m -3/-7=3/7=m answer D) 3/7
 Mixture_Word_Problems/252459: How many grams of pure silver and how many grams of an alloy that is 65% silver should be. melted together to produce 56g of an alloy that is 80% silver?1 solutions Answer 184372 by richwmiller(9143)   on 2009-12-28 12:15:18 (Show Source): You can put this solution on YOUR website!x+.65(56-x)=56*.80 x+36.4-.65x=44.8 .35x+36.4=44.8 .35x=8.4 multiply by 100 to remove decimals 35x=840 x=24 grams of pure silver are added to 32 grams of 65% silver check 1*24+.65(32)=56*.80
 Miscellaneous_Word_Problems/252462: when N is divided by 5, the remainder is 3. what is the remainder when 7N is divided by 5?1 solutions Answer 184371 by richwmiller(9143)   on 2009-12-28 12:05:46 (Show Source): You can put this solution on YOUR website!n/5=x+3 7n/5=y n=5(x+3) n=5x+15 7*(5x+15)/5 7*(x+3) 7x+21 21/7=3 no remainder 7x/7=x no remainder So there is no remainder
 Word_Problems_With_Coins/252460: i have 4 philippine coins in my pocket. If none of them is a 5 centavos or a 10 cents, what could be the amount?1 solutions Answer 184370 by richwmiller(9143)   on 2009-12-28 12:02:20 (Show Source): You can put this solution on YOUR website!What denominations are there in Phillipine coins? what is their total value?
 Money_Word_Problems/252461: Rena has a 23 pesos and 75 centavos worth of coins in her purse. What coins could they be? what is the list of number?1 solutions Answer 184369 by richwmiller(9143)   on 2009-12-28 12:01:07 (Show Source): You can put this solution on YOUR website!What country's pesos are we talking about? What denominations are available in pesos and centavos?
 Geometry_Word_Problems/252458: If a regular octagon has a side-length 1, find the distance between opposite sides.1 solutions Answer 184368 by richwmiller(9143)   on 2009-12-28 11:58:33 (Show Source): You can put this solution on YOUR website!if one side is 1 unit 2a^2=1^2 a^2=1/2 a=sqrt(1/2) distance = 2sqrt(.5)+1 which is twice one leg of the right isosceles triangle with hypotenuse of 1 plus one for the one unit side
 Polygons/252457: A regular polygon has an interior angle that measures 144 degrees, and a side of which is 12 units long. What is the perimeter of the regular polygon?1 solutions Answer 184367 by richwmiller(9143)   on 2009-12-28 11:53:28 (Show Source): You can put this solution on YOUR website!n= number of sides sum of angles=180(n-2) 180(n-2)/n=144 n=10 10*12=120 units
 Number-Line/252439: How to put these sets of numbers in appropriate place on numberline? 18/37, -2/5, 1 3/7, -2.7, 13/14, 7/31 solutions Answer 184349 by richwmiller(9143)   on 2009-12-28 10:14:05 (Show Source): You can put this solution on YOUR website!probably the easiest way is to convert them to decimals for example 18/37=.486486486486 before you convert 1 3/7 convert to an improper fraction 10/7 which equals 1.4285 I will leave the others as an exercize for you