According to a study, children ranging from ages 8 to 18 averaged 7.4 hours per

Question

According to a study, children ranging from ages 8 to 18 averaged 7.4 hours per day using electronic media. Assume the population standard deviation is 2.1 hours per day. A random sample of 30 children from this age group was selected, with a sample average of 8.2 hours of electronic media use per day. Complete parts a and b below. a. Is there support for the claim of the study using the criteria that the sample average of 8.2 hours falls within the symmetrical interval that includes 95% of the sample means if the true population mean is 7.4 hours? 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.) 0 A The probability P x2 82-0 This indicates that the sample average of 8.2 hours falls outside the 95% symmetrical O B. The probability P x2 8.2)- This indicates that the sample average of 8.2 hours falls within the 95% symmetrical interval, supporting the claim of the study.

Explanation / Answer

heer P(Xbar>=8.2)=P(Z>(8.2-7.4)/(2.1/sqrt(30))=P(Z>2.09)=0.0183 ( please try 0.0185 if this comes wrong)

option A is correct : the probability P(Xbar>=8.2)=0.0183(please try 0.0185 if this comes wrong)

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