There are 12 boys and 16 girls in Marco's class (including Marco). What is the probability that a student chosen at random from Marco's class will be a boy? 4/7, 3,7, or 2/5.

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.

Two sides of a triangle mesure 20cm and 30cm. what is the measure of the third side

Quadrilateral abcd in the figure below represents a scaled-down model of a walkway around a historic site. quadrilateral efgh represents the actual walkway. abcd is similar to efgh. what is the total length, in feet of the actual walkway?