The frequency of carriers of this disease is 0.02 in a particular population. Consider many couples like 6 and 7 where one parent is affected and the other is unaffected. On average, what is the chance that the first child of these couples will be affected? Please give a number between 0.0 and 1.0

Since both genes (dominant) from one parent are for normal development, the chances for any child are 50% to be a carrier, but none will have the disease.