Red hair (autosomal recessive) is found in approximately 4 percent of the people in Norway

Red hair (autosomal recessive) is found in approximately 4 percent of the people in Norway. If we assume that the Norwegian population is in Hardy-Weinberg equilibrium with respect to hair color:

a) What are the frequencies of the red hair (r) and non-red hair (R) alleles?
b) What is the frequency of heterozygotes?
c) What proportion of all marriages could potentially have a child with red hair?