If z varies directly as x and inversely as y, and z = 8 when x = 12 and y = 3, the value of the constant of proportionality is what number?

2 Answers
Nov 13, 2017

k=2

Explanation:

when z varies directly proportional to x means a division

c=zx where c is a constant of proportionality

when z varies inversely proportional to x it means a product

zy=c

now with both

k=zyx

z=8;x=12andy=3

k=8.312

k=2

Nov 13, 2017

k=2

Explanation:

the initial statement is zxy

to convert to an equation multiply by k the constant
of variation

z=k×xy=kxy

to find k use the given condition

z=8 when x=12 and y=3

z=kxyk=yzx=3×812=2412=2