A square has side of length 7.23, find the length of its diagonal

Suppose a man is heterozygous for heterochromia, an autosomal dominant disorder which causes two different‑colored eyes in an individual, produced 25‑offspring with his normal‑eyed wife. of their children, 15 were heterochromatic and 10 were‑normal. calculate the chi‑square value for this observation.

When y’all answer can y’all explain too !

Pranza plotted point a in the coordinate plane below.