Question 74947
The manufacture’s current guess is that 60 % of the combines sales of the two products next year maybe of beta type but is going to confirm his hypothesis by having sales representative call on a sample of buyers to learn how much alpha and beta they intend to buy. 
How large a sample size would they call if he the manager decided that tolerable error in estimating error in estimating the population proportion is not to be greater than 2 % at confidence level of 99 % .

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E = z*sqrt(pq/n)
Interchange E and sqrt(n) to get:
sqrt(n) = (z*sqrt(pq))/E
Let P=0.6, based on the guess.
sqrt(n) = (2.326sqrt(0.6*0.4))/0.02
sqrt(n) = 5.698365...
n=32 when rounded to a whole number
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Cheers,
Stan H>