Find y when x=15 if y=16 when x=30.

Question

dayakar · Answer

question is incomplete

anonymous · Answer

Its not..Its exactly what it says...

anonymous · Answer

Its Direct Variation

sasogeek · Answer

it is complete @dayakar

sasogeek · Answer

y:15
16:30

find y?

dayakar · Answer

x ,y are in direct variation
x1/y1 = x2/y2

anonymous · Answer

Ummm...I dont understand..

dayakar · Answer

15/16 = 30/y

simplify it

dayakar · Answer

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sasogeek · Answer

when x=30, then y=16
if x=15, then what is the value of y

that is, 30 is to 16, as 15 is to what (y)?
to answer that, we do y1/x1 = y/x2 and solve for y

y1=16
x1=30
x2=15
so our equation resolves to 
16/30=y/15
16*15/30 = y

solve for y

dayakar · Answer

in this ratio of x and y = constant

dayakar · Answer

@sasogeek  my approach is also correct,i will show u

sasogeek · Answer

you approach doesn't answer the question... it is a solution, but not a solution to the problem we have here...

dayakar · Answer

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sasogeek · Answer

that makes no sense, because it's not an exponential function. it's linear. when x is 30, y is 16. how is it that when x is 15, y is 32?

sasogeek · Answer

you got it wrong from the very beginning. it's supposed to be 16:30, and not 15:16....

sasogeek · Answer

for x
x1 = 30
x2 = 15 = 30/2

for y
y1 = 16
y2 = 8 = 16/2

the constant is 2, and it is a multiplier.... it's a linear function

dayakar · Answer

@sasogeek plz ,can u show your work

dayakar · Answer

@sasogeek 
x,y are in direct variation you did it indirect variation plz check again

sasogeek · Answer

when x increases, y increases
and when x decreases, y decreases

16:30 = y: 15
=> 16/30 = y/15

16*15 / 30 = y
240 / 30 = y
8 = y
y= 8


therefore,

16:30 = 8:15
0.53 = 0.53


(8*2) : (15*2) = 8:15

dayakar · Answer

given x=15 and y= 16
 if         x = 30 [increased]    y=32 [increased]

sasogeek · Answer

you got it all twisted
according to the question,
given x=30 and y=16
then if x=15,   y = what? it has to be less than 16 because x has decreased, the value of y must also decrease

dayakar · Answer

@jabez177 ,plz,do u explain whose approach is correct

anonymous · Answer

You both are confusing me....

anonymous · Answer

@mathmale Can you help please?

dayakar · Answer

@Angel360 , i am sorry,
wait some time for a good explantion

sasogeek · Answer

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