If x varies inversely as y and x = 48 when y = 4, find y when x = 3.

A. y = 16
B. y = 12
C. y = −4
D. y = 64

Question

If x varies inversely as y and x = 48 when y = 4, find y when x = 3. 
    
A. y = 16
B. y = 12
C. y = −4
D. y = 64

aroub · Answer

Because it varies inversely so it's, xy=k, we just substitute the values that are given in the equation to find k: 

xy=k
48(4)=k
192=k 

xy=k
3(y)=192
y=64

aroub · Answer

And you can also use this way: 

x1*y1=x2*y2 

(i think it's easier)

anonymous · Answer

how about this one?

anonymous · Answer

If x varies inversely as y and x = 10 when y = 20, find y when x = 25. 
    
A. y = 8
B. y = 5
C. y = −10
D. y = 4

aroub · Answer

What about you try? :)

anonymous · Answer

i've already did and couldnt get it and i've asked someone on here and they couldnt figure it out

aroub · Answer

O.o Okay I'll do it but using the second way. 

x1*y1=x2*y2
10(20)=25(y)
200=25y
y=8