Posted by Anonymous on Friday, January 25, 2013 at 12:50pm.
Use the normal approximation to the binomial distribution.
mean = np
standard deviation = √npq
Therefore:
mean = .94n
standard deviation = √(n)(.94)(.06) = √(.0564n)
Using z-scores:
z = (x - mean)/sd
With the data:
1.645 = (160 - .94n)/√(.0564n)
Solve for n.
(Hint: Round answer to 165.)
For Further Reading