In a typical monohybrid cross of truebreeding tall TT and sh

In a typical monohybrid cross of true-breeding tall (TT) and short (tt) Pisum sativumparents, what would be the expected number of heterozygous tall plants in the F2 offspring, assuming that T is dominant to t, and 80 offspring are counted?

I got 30 as an answer, but the correct answer was 40. I feel like I\'m missing something here. Any thoughts?

Solution

simple f2 genotypic ratio would be 1:2:1

1 HOMOZYGUS TALL (TT)2 HETEROZYGUS TALL(Tt) AND 1 HOMOZYGUS short (tt)

so if total are 80

ratio of 1:2:1 would split as 20:40:20

so heterozygus tall would be 40

or let us calculate it this way

2/4 multipied by 80 (total) = 40 ......................(1+2+1= 4 (total ) ,,, and 2 are heterozygus tall so 2/4)

hope it helps