Question 1150681
n = 80
p = 0.65
q = 0.35
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M = np = 80(0.65) = 52
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SD = {{{sqrt(n*p*q)}}} = {{{sqrt(80*(0.65)*(0.35))}}} = {{{sqrt(18.2)}}} = 4.266
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"At most 47" means 47 or fewer.
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P(x <= 47) ---> P(x < 47.5)
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z = {{{(47.5 - M)/(SD)}}} = {{{(47.5 - 52)/(4.266)}}} = {{{(-4.5)/(4.266)}}} = -1.05
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Look up -1.05 on a z-table.  The result is 0.1469.  So, there is a 0.1469 chance that at most 47 companies have growth in sales revenue within one week of the first appearance of the advertisement.