I was doing some past year papers when I came across this question, never been able to do such questions ever since Sec 2, >.<
When some oil floats on water, its upper surface is a circle.
The thickness, t, of the oil is inversely proportional to the square of the radius, r, of the circle. When t = 18, r = 200.
Find t when r = 300.
I know the formula for inverse proportion is y=k/x but I have no idea how to see which is y and which is x, and how to derive k, the constant. Any math pro can help me?
the first variable is the y while the second is the x .
t = K / r ^2
18 = K /200^2
18= K/4000
K = 20000
t = 20000/r^2
t = 20000/(300*300)
t=0.22metres
you got it tmarcus ?
which other question you dont understand ? practice more , thanks