Step 1: Calculate the total number of snails in the sample
= 275 + 150 + 75
= 500
Step 2: Calculate the total number of pink-shelled snails (genotypes: CᴾCᴾ and CᴾCʸ)
= 275 + 150
425
Step 3: Calculate the phenotype frequency of pink-shelled snails
Phenotype frequency = (total individuals with phenotype ÷ total individuals in population) × 100
= (425 ÷ 500) × 100
= 0.85 × 100
= 85%
Step 4: Calculate the phenotype frequency of yellow-shelled snails
Phenotype frequency = (total individuals with phenotype ÷ total individuals in population) × 100
= (75 ÷ 500) × 100
= 0.15 × 100
= 15%