Tay Sachs disease is a fatal disorder in children (usually by age 5) that causes a progressive degeneration of the
central nervous system. It is caused by the absence of an enzyme called hexosaminidase .A (or hex A). Without hex A, a fatty substance builds up on the nerve cells in the body, particularly the brain. In some eastern European populations as many as 1 in 25 adults may be heterozygous for the condition.
What is the frequency of adults homozygous for the normal allele in this population?