A pizza shop claims its average home delivery time is 22 minutes. A sample of 30

Question

A pizza shop claims its average home delivery time is 22 minutes. A sample of 30 deliveries had a sample average of 25.6 minutes. Assume the population standard deviation for the shop's deliveries is 6.9 minutes. Complete parts a and b below. a. Is there support for the shop's claim using the criteria that the sample average of 25.6 minutes falls within the symmetrical interval that includes 95% of the sample means if the true population mean is 22 minutes? Select the correct choice below and fill in the answer box within your choice. (Type an integer or decimal rounded to four decimal places as needed.) A. . This indicates that he sample average of 25. minute alls outside the 95% symmetrica intera contradicting hes osc am Thisindicates that the sample average of 25 6 minutes falls within he 95% symmetrica inte supporting the shop scam. The probability P x225.6 B. The probability P x2256)=

Explanation / Answer

a)

option A is correct : the probability P(Xbar>=25.6)=0.0021) this indicates that ...............

b)

for middle 95% values ; critical z =1.96

hence corresponding values =mean -/+z*std deviation =19.5309 ; 24.4691

for normal distribution z score =(X-?)/? here mean=       ?= 22 std deviation   =?= 6.9 sample size       =n= 30 std error=?x?=?/?n= 1.2598

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