Question

Sickle cell anemia is known to run in a family. A pedigree chart for this family is shown below

What percentage of the offspring are carriers of the disease but do not have it ?

Answer 1

In pedegree charts, 
a square stands for a male
a circle, female
black filled: phenotype expressed
half filled, heterozygous, hence carriers.

So according to the pedigree diagram, two of the four offsprings (both daughters) are heterozygous, or carriers, of sickle cell anemia.

Answer 2

The answer is 50%  Hopethis helps!