The meiotic products of a trisomic can be shown in the following diagram:
In the above figure three segregations occur. This segregation results in the overall gametic ratio as shown below:
• 1/6 A
• 2/6 a
• 2/6 A/a
• 1/6 a/a
Each type of segregation is equally likely to occur. Taking 100 as the total, since all the three have equal chances of segregation, the percentage of each type of segregation would be 33.3%.