Solutions For An Introduction to Genetic Analysis Chapter 4 Problem 10P

The RF between A/a and B/b in a cross in which all the meioses have four-strand double crossovers in that region can be calculated in this way:

The above figure shows that a single four-strand double crossover produces 100% RF for that meiosis. When all the meioses have four-strand double crossovers, the overall RF would be 100%.