Final answer:
The genotypic ratio of the children would be 1 YY : 2 YR : 1 RR. The phenotypic ratio would be 3 yellow-haired : 1 red-haired.
Step-by-step explanation:
In pea plants, yellow hair (Y) is dominant over red hair (R). When a yellow-haired person is crossed with a strawberry-blonde person, the genotypic ratio of the children would be 1 YY : 2 YR : 1 RR. The phenotypic ratio would be 3 yellow-haired : 1 red-haired.