Question

Out of every three individuals of an extinct animal, two of the three carried a defective gene. How many animals carried the normal gene in a population of 300?

Answer 1

100 of the population carried the normal gene.

Answer 2

It is given that out of three individuals of an extinct animal two of which  carries defective gene which can be represented as $\frac{2}{3}$.

Number of animals which carried normal gene

     $1 -\frac{2}{3}\\\\=\frac{1}{3}$

If total number of population of animal=300,then

Number of animals which carried normal gene

  $=\frac{1}{3}\times 300=100$

=100 animals