Bosco

In physics, Ohm's law says that current through a wire, I, is directly proportional to voltage, V, and inversely proportional to resistance, R:
I = V/R  
It's also true that resistance is directly proportional to the length of the wire.  We have a piece of wire.  We pass 60 volts through this wire and measure 200 milliamps of current.  If I cut the wire in half and pass 400 volts through it, how many milliamps of current will I measure?   

We begin with the basic V = IR from which R = V / I and I = V / R    

V is in Volts.   I is in Amperes.   R is in Ohms.   

V = 60 Volts   

I  = 200 mA = 0.2 Amp  

                                                                R  =  V / I  

                                                                R  =  60 / 0.2  

                                                                R  =  300 Ohms   

When you cut the wire in half,   

the resistance of one piece of   

it is half of what the total was.  

New V = 400 Volts   

New R = 150 Ohms  

                                                                I  =  V / R    

                                                                I  =  400 / 150  

                                                                I  =  2.6667 Amps  

There are 1000 mA per Amp, thus          I  =  2666.7 mA  

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This is my "negative money" answer. 

I answered this problem a week ago. 

This is a copy / paste of that answer.    

Alice and Bob each have a certain amount of money. If Alice receives n dollars from Bob, then she will have 4 times as much money as Bob. If, on the other hand, she gives n dollars to Bob, then she will have 8 times as much money as Bob. If neither gives the other any money, what is the ratio of the amount of money Alice has to the amount Bob has?    

                                        (A + n)  =  4 • (B – n)   

                                         A + n    =  4B – 4n    

                                         A – 4B  =  –5n                   (1)    

                                         (A – n)  =  8 • (B + n)   

                                          A – n    =  8B + 8n   

                                          A – 8B  =  9n                    (2)   

Multiply both sides  

of (1) by 9                        9A – 36B  =  –45n              (3)    

Multiply both sides  

of (2) by 5                        5A – 40B  =    45n              (4)      

Add (3) and (4)               14A – 76B  =  0   

Add 76B to both sides               14A  =  76B   

Divide both sides by 76B   

                                                  14A          1    

                                                  ––––   =   ––    

                                                  76B           1                       

Multiply both sides by 76/14    

                                                      A          76                         38

                                                    –––   =   –––   reduces to   –––   

                                                      B          14                          7   

It works if you accept the  

concept of negative money.  

That is, n must equal –2 dollars.  

Say Alice has 38 and Bob has 7        

                                                     (38 + n)  =  4 • (7 – n)     

                                                      38 + n   =  28 – 4n    

                                                             5n  =  –10     

                                                               n  =  –2       

and               

                                                     (38 – n)  =  8 • (7 + n)    

                                                      38 – n   =  56 + 8n      

                                                          –9n   =  18    

                                                               n  =  –2       

_.

>>>> probably to boost their ego through imaginary internet points <<<<   

Maybe you'd get more satisfaction by commenting on things you actually know something about, if anything fits that description.  To the contrary, solving problems here is a humbling experience for me, when I see the number of math problems that I not only (1) don't know how to solve, but also (2) don't even recognize some of the math terminology they use. 

Some of these probably are students bringing their homework here.  But even if I do solve a problem for them, if somebody hadn't shown them, then they wouldn't have seen how to do it at all.  It's to their own advantage to try to learn something from the responders' efforts.  Responders who try to help, that is; not responders like the scolds hiding behind "Guest" postings who imagine themselves the self-appointed conscience of the site.  

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@history, you posted while I was still typing up my answer.   

Oh well, it should be encouraging to the OP that we corroborrated each other's answer.  

Unlike Post #1 who I think is a troll who deliberately posts wrong answers because     

she/he thinks that everyybody who asks for help here is cheating on their homework     

and should be punished.   

_.

Find the number of square units in the area of the triangle.    

Let's start by remembering that a straight line can be represented by y = mx + b,  

where m stands for the slope of the line and b stands for the y-intercept. 

We have two points on the line so let's use those.   First, determine m.  

                                                            Δy          (6)  –  (2)          4   

                                                   m  =  –––  =  ––––––––––  =  –––  =  1   

                                                            Δx         (–2) – (–6)          4  

Now we're getting somewhere.  Let's use one of those points to determine b. 

                                                   y  =  mx + b    

                                                   2  =  (1)(–6) + b   

                                                   2  =  –6 + b   

                                                   b  =  8    

So, the formula for the line is      y  =  x + 8       

So,  when x is 0, y is 8  

and when y is 0, x is –8.   

That makes each leg of the triangle 8 units long.    

And it's a right triangle because the origin is a right angle.  

Therefore, we can calculate the area as           A  =  (1/2)(Base)(Height)   

                                                                          A  =  (1/2)(8)(8)    

                                                                          A  =  32 square units   

_.

@HumenBeing   >>>Post #1 probably isn't the real GA.... <<<    

Post #1 obviously isn't the real original GA, for the reason you gave.  But she/he might be a different GA.  

It could stand for Gene Autry, or George Armstrong, or Geronimo, Arizona. There actually is such a place.    

The simplest solution would be for this recently-posting GA to register an account and sign in every time.   

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Praise from Caesar.  Thank you.  Say goodnight, Ginger.  :-)   hehe a little joke 

_.

In triangle PQR, M is the midpoint of PQ. Let X be the point on QR such that PX bisects angle QPR, and let the perpendicular bisector of PQ intersect AX at Y. If PQ = 36, PR = 36, QR = 16, and MY = 50, then find the area of triangle PQR   

We don't need all those midpoints and angle bisectors and whatever MY is.   

We have the three sides of a triangle, and that's all we need to find its area.  

We could still get the area, but it's an isoceles triangle, and that makes it easier.  

The sides:     PQ = 36, PR = 36, QR = 16     

This tells us that triangle PQR is an isoceles triangle, with angle P at the apex.  

So drop a perpendicular line from P down to base QR, intersect at point J.   

This does two things.  It bisects QR and it creates two right triangles.    

So use Pythagoras' formula to determine the length of this perpendicular,  

which, conveniently for us, is also the height of PQR.  

PJ² = 36² – 8²    ----->   PJ² = 1296 – 64   ----->    PJ = 35.1   

Area of PQR  =  (1 / 2) • base • height  =  (1 / 2) • 16 • 35.1  =  280.8    

check answer    

per Heron's Formula, Area  =  sqrt of (44)(8)(8)(28)  = sqrt(78,848)  =  280.8   

Confirmed.  I love it when a plan comes together.    

_.

All members of our painting team paint at the same rate. If 20 members can paint a 2000 square foot wall in 30 minutes, then how long would it take the  members to paint a 2000 square foot wall, in minutes?      

If the painting team can paint a 2000 square foot wall in 30 minutes, then  

long would it take them to paint a 2000 square foot wall, in minutes?   

There must be something missing from this problem.     30 minutes.  

_.

Hi, HumanBeing.  It stumped me, so I must not have a brain.     

Would you mind posting a solution, just for my benefit?   

_.