Question

can anyone help me with this ratio and proportion problems

Answer 1

If v is inversely proportional to x and y, and if v=20 when x=2 and y=8, find v when x =4 and y=10.

Answer 2

@Nnesha

Answer 3

@kropot72

Answer 4

You've been spamming this question constantly without giving anyone a chance to answer it, so no.

Answer 5

I believe we use the formula:

\(y = \dfrac{k}{x}\)

Answer 6

how about v?

Answer 7

I believe we replace 'x' with 'v'..

Answer 8

Maybe..It's a confusing question..

\(y = \dfrac{v}{x}\)

Answer 9

Just leave the variables as it is, and use the same methods of inverse proportions as \(y = \dfrac{k}{x}\).

Answer 10

I don't know how to fit in the 'v' though..

Answer 11

:D

Answer 12

Can you help out with this question? @Supreme_Kurt

Answer 13

Wait..maybe we find the constant and use those to set up a proportion..

Answer 14

Just Kurt.
And I'm a bit confused about what it means for a value to be inversely proportional to two values.

Does it mean it's inversely proportional to their product?

Answer 15

The constant when x = 2 and y = 8 is 16.

The constant when x = 4 and y = 10 is 40.

v = 20 when the constant is 16

Find v when the constant is 40.

Set up a proportion:

\(\dfrac{20}{16} = \dfrac{x}{40}\)

Idk if that's right..

Answer 16

Yay, hartnn! :D

Answer 17

Just kidding. I am not sure either.

Answer 18

v= k/(xy)

Answer 19

Oh I was close....

Answer 20

Ohhhh

Answer 21

That explains it all :P

Answer 22

so that IS what it meant, then?
That for v to be inversely proportional to x and y, it means that v is inversely proportional to xy after all?

I thought v had to be inversely proportional to x AND inversely proportional to y...

Answer 23

both mean the same thing kurt :)

Answer 24

\(v = \dfrac{k}{xy}\)

Plug in what we know:

\(20 = \dfrac{k}{(8)(2)}\)

Is this how we set it up..or..?

Answer 25

I've never learned this before xD

Answer 26

No they don't.
If it means v is inversely proportional to xy, then x is inversely proportional to y
If it means v is inversely proportional to x AND y, then x is directly proportional to y.

Answer 27

1. v = k/xy

2. v = k1/x, v = k2/y
which indirectly implies
v= k1k2/(xy) = k/(xy)

Answer 28

oh wait... derp

Answer 29

If it means v is inversely proportional to x AND y, then x is directly proportional to y. NOPE

Answer 30

x can never be directly proportional to y in any cases here

Answer 31

iGreen, thats correct.
find k

Answer 32

\[\Large vx = k_1\]\[\Large vy = k_2\]
\[\Large \frac{vx}{vy}=\frac{k_1}{vy}\]
\[\Large \frac{vx}{vy}=\frac{k_1}{k_2}\]

\[\Large \frac{x}{y}=\frac{k_1}{k_2}=k\]

Answer 33

Are we proving inverse and direct proportionalities ? :D

Answer 34

Kurt is confused :3
And we are dealing with poor Kurt's confusion D:

Answer 35

\(\color{blue}{\text{Originally Posted by}}\) @hartnn
1. v = k/xy

2. v = k1/x, v = k2/y
which indirectly implies
v= k1k2/(xy) = k/(xy) <<<<<<MY MISTAKE, that should be v^2
\(\color{blue}{\text{End of Quote}}\)


so you're right, kusrt :)

Answer 36

dangit, hart
you gave me a hart...attack.

haha

Answer 37

if v is inversely proportional to x and inversely proportional to y,
then x and y are directly proportional.

which is not the case here.

Answer 38

brb guys, I think I've passed enough of my own confusion to OP.
I'll just have dinner :3

Answer 39

Im confusing everyone here.

Answer 40

\(\color{blue}{\text{Originally Posted by}}\) @iGreen
\(v = \dfrac{k}{xy}\)

Plug in what we know:

\(20 = \dfrac{k}{(8)(2)}\)

Is this how we set it up..or..?
\(\color{blue}{\text{End of Quote}}\)

continue, find k here

Answer 41

Okay, can you do that? @TheKinslayer

Answer 42

so its the final formula then?

Answer 43

yep,

v= k/(xy)

Answer 44

ok ty guys can you help me with this another problem out here

Answer 45

what did you get the value of v finally ? just to check....
and yes

Answer 46

wait im still working with it

Answer 47

i got v=8

Answer 48

\(\huge \checkmark \)

Answer 49

who can i grand the best response?

Answer 50

here is the other problem..

Answer 51

The distance fallen by a body, starting from a position of rest in a vacuum near the easrth's surface, is proportional to the square of the time occupied in falling. If a body falls 256 ft. in 4sec, how far will it fall in 11 sec?

Answer 52

Proportion this time is direct :)
And when two values are in direct proportion, their QUOTIENT will be the same, no matter what :)

Now, read through the problem again and tell me which two values are in direct proportion ^^

Answer 53

Btw, you should post this in a new question.

Answer 54

ok