There are chances of 75% solid green coloured rind in watermelons.
Explanation:
Dominant trait = Solid Green rind G
Recessive trait= stripes g
Given that both the parent plants are heterozygous so their alleles will be
Gg Gg
From the Punnet square
     G     g
G Â Â Â GG Â Â Gg
g    Gg   gg
The phenotype ratio is 3:1 Â ( 3 watermelons with the green colour rind and 1 with striped rind observed)
Genotype ratio is 1:2:1
From the observation, we can say that 75% of the watermelons will have solid green colour rind because G is dominant over g.