The question is asking for a "rough estimate" but lots of folks just describe how to calculate the value exactly. This makes the following question redundant. Either drop this question or make clear that we want a "method for getting a rough estimate by eye".
The question is asking for a "rough estimate" but lots of folks just describe how to calculate the value exactly. This makes the following question redundant. Either drop this question or make clear that we want a "method for getting a rough estimate by eye".