Math or Bio

Let A = 30 cm height and a = 20 cm height mom $A_{1}$ $A_{2}$ $A_{3}$ $A_{4}$ $A_{5}$ $a_{6}$ = 170 cm height dad $A_{1}$ $a_{2}$ $A_{3}$ $A_{4}$ $a_{5}$ $a_{6}$ = 150 cm height What is the probability of son's height = 160 cm ps. Please calculate in Biology way (polygene)