2 races of corn, averaging 48 to 88 inches in height
respectively, are crossed. the F1 is quite uniform, averaging 68
inches tall. The F1 are self fertilized to give an F2. Of 512 F2
plants, only 2 are as short as 48 inches, and 2 are as tall as 88
inches. How many polygene LOCI are involved in this trait?