How to interpolate the correction factor F

[anonymous99]

Homework Statement

I'm working on a heat exchanger problem. The problem requires me to determine the heat transfer area for a shell-and-tube exchanger. I need the correction factor F to solve this problem but I'm not sure how to interpolate the chart below for it. I've worked out the temperature effectiveness P to be 0.28 and the Heat Capacity Ratio R to be 3.62 so how would I interpolate the chart to get a more accurate correction factor? I know to use the gradient but not sure how to apply it here.

Relevant Equations

The values on the x-axis are P. Each curve corresponds to a value of R.

 

[.Scott]

According to the graph, for R=3.62, the maximum value for P is about 0.24.
Your value of P=0.28 would seem to be in error.