Suppose that w is directly proportional to the square of L

[georgebaseball]

Suppose that w is directly proportional to the square of L and inversely proportional to A. If w = 4 when L = 2 and A = 10, find w when L = 5 and A = 20.

This is how I have been trying to solve it:

w = (KL^W)/A

Then I solve:

w = (k*4*4)/10 = 1.6

Then I replace 1.6 for k:

k = 1.6*25/20 = 2

But the book says the answer is 12.5. I don't get it. Please help me. Thank you!

 

[arthur ohlsten]

w is proportional to the square of L means:" is" becomes=, and square of Lbecomes L times L or L^2, and K is the constant of proportionality
W=KL^2

W is inversely proportional to A means:
W=K/A

our equation is:
W =KL^2/A
let L=2 A=10 and W=4, find K
4=K4/10
K=40/4
K=10

let L=5 and A=20, find W
W=10[5^2]/20
W=12.5

Arthur

 

[georgebaseball]

thank you arthur!