A government agency has specialists who analyze the frequencies of letters of th

Question

A government agency has specialists who analyze the frequencies of letters of the alphabet in an attempt to decipher intercepted messages. In standard English text, a particular letter is used at a rate of 6.2%. a. Find the mean and standard deviation for the number of times this letter will be found on a typical page of 3500 characters. mu = sigma = (Round to one decimal places as needed). b. In an intercepted message, a page of 3500 characters is found to have the letter occurring 262 times. Is this unusual? A. Yes, because 262 is within the range of usual values. Click to select your answer(s).

Explanation / Answer

Answer tp the question as below:

p = .062, n = 3500

a.

Mean = np = .062*3500 = 217
Sigma = sqrt(p0*p0'/n) = sqrt(.938*.062/3500) = .0041

b.

p' = 262/3500 = .075
Z = p'-p0/ sqrt(p0*p0/n) = (.075-.062)/.0041 = 3.17
Any Z value of above 3 means that the p value is less than .15
So, this is unusual.

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