If you know the fragment sizes in the HindIII digest, how do you determine the fragment sizes in an unknown sample? You use data from the marker to prepare a standard curve, which will provide a standard for comparison to the unknown fragment sizes. Using a standard to estimate an unknown is sometimes called "interpolation"; you will interpolate the size of the unknown fragments.

You begin by making a standard curve for the known sample, DNA plus HindIII. Measure the distance each HindIII fragment migrated on the gel and then complete the chart. It is very difficult to get exact numbers as you read this graph. If your response is in a close range, that is acceptable.