Expected fitness of the b/b homozygote relative

The genotype frequencies of a two allele polymorphism were measured from a sample of 200 individuals. The results were:

Genotype A/A A/B B/B

Frequencies 0.0 0.4 0.6

Does this represent a significant departure from the Hardy-Weinberg ratios? Further studies show that the absence of the A/A genotype is due to the lethal effect of the A allele when homozygous. Assuming that the measured gene frequencies are equilibrium values, what is the expected fitness of the B/B homozygote relative to the heterozygote?

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