Suppose that w and t vary inversely and that t = 1/5 when w = 4. Write a function that models the inverse variation, and find t when w = 9.

Would it be t=1/5w; 4/45 or 4/5w; 4/45?

The correct answer to this question is this one: "4/45"

inverse variation - - - > wt = constant let wt=k put w=4, t = 1/5 and find k

So the correct answer for k is 4/5

wt = 4 * (1/5) = 4/5 = k/

so your function is

wt = 4/5 or t = 4 / (5w)

now to get t, when w=9, just put w=9 in t=4 / (5w)

So that makes 4/45