Mendel crossed true breeding green-seeded pea plants with true
breeding yellow-seeded pea plants by cross-pollination to generate
F1 hybrids. When he selfed (not cross-pollinated) the F1 hybrids,
he got a ratio of 3:1 of yellow to green seeds (F2) in the pods of
these hybrids. When he planted just the yellow seeds, what
proportion of these would give rise to plants with pods carrying
both yellow and green seeds (F3 generation)?  Please
provide solution, thank you!!!