Find a Mathematical Model Representing the Statement $( z = 128 \text { when } x = 4 \text { and } y = 8 . )$

question 407

Multiple Choice

Find a mathematical model representing the statement.(Determine the constant of proportionality.)
Z varies jointly as x and y. $( z = 128 \text { when } x = 4 \text { and } y = 8 . )$

• A) \(z = \frac { 4 y } { x }\)
• B) \(z = \frac { 4 } { x y }\)
• C) \(z = \frac { x y } { 4 }\)
• D) \(z = \frac { 4 x } { y }\)
• E) \(z = 4 x y\)