converging data

[supes927]

I'm wondering if there is a way of using any excel/vba functions to predict where two sets of data will meet. I can't see a way to use Forecast for this.

EG:
Set 1 - 10,25,40,90 (Low values increasing)
Set 2 - 200,190,185,150 (Higher values decreasing)

After a certain amount of iterations if the trends are linear the values from Set 1 & Set 2 will correspond. Does Excel provide for this or will I have to brush up on my math?

[p45cal]

I don't know of a worksheet function, so perhaps it is back to the maths books:
x values A2:A5 (assumed 1,2,3,4)
y1 values B2:B5
y2 values C2:C5

cross over x (put into E2 for use by last formula below):
=(INTERCEPT(C2:C5,A2:A5)-INTERCEPT(B2:B5,A2:A5))/(SLOPE(B2:B5,A2:A5)-SLOPE(C2:C5,A2:A5)) cross over y:
=((SLOPE(C2:C5,A2:A5)*INTERCEPT(B2:B5,A2:A5))-(SLOPE(B2:B5,A2:A5)*INTERCEPT(C2:C5,A2:A5)))/(SLOPE(C2:C5,A2:A5)-SLOPE(B2:B5,A2:A5)) but cross over y can be calculated more simply by using the first formula result:
=SLOPE(B2:B5,A2:A5)*E2+INTERCEPT(B2:B5,A2:A5)
(x=5.914, y=128.323)