A manufacturer of large-screen televisions wants to compare with a competitor the proportions of its best sets that need repair within 1 year. If it is desired to estimate the difference between proportions to within

.05 with 90% confidence, and if the manufacturer plans to sample twice as many buyers (n,) of its sets as buyers (n,) of the competitor's sets, how many buyers of each brand must be sampled? Assume that the proportion of sets that need repair will be about .2 for both brands.