Question

UUUUUUUUUU TULUNUM i 9.35 Experian Marketing Services reported that the typical Amer- ican spends a mean of 144 minutes (2.4 hours) per day accessing the Internet via a mobile device. (Source: The 2014 Digital Mar keter, available at ex.pn/1kXJjfX.) In order to test the validity of this statement, you select a sample of 30 friends and family. The results for the time spent per day accessing the Internet via mobile device in minutes) are stored in InternetMobile Time a. Is there evidence that the population mean time spent per day accessing the Internet via mobile device is different from 144 min- utes? Use the p-value approach and a level of significance of 0.05. b. What assumption about the population distribution is needed in order to conduct the t test in (a)? c. Make a list of the various ways you could evaluate the assump- tion noted in (b). d. Evaluate the assumption noted in (b) and determine whether the test in (a) is valid.

I have attached the data from the excel spreadsheet. 1 - 31. please show all work.

Answer 1

a) Null hypothesis H0: minutes

u= 144

Alternative Hypothesis Ha: Minutes

ᎭL£f

alpha=0.05

t= 175.27-144/139.84/sqrt(30)

t= 31.27/139.84/5.48

t= 31.27/25.52

t= 1.23

degrees of freedom= n-1=30-1=29

The p-value is .228582.The result is not significant because p < .05.

Decision: REJECT NULL HYPOTHESIS H0.

Conclusion: We have sufficient evidence to conclude that the population mean is different from 144 minutes.

b) i) random sampling

ii) normality of data distribution

iii) population variance unknown.

c) For normality we can draw Q-Q plot Histogram.

d)

Normal Q-Q Plot of VAR00005 Expected Normal Value . ooooo do o 0 400 600 200 Observed Value

Since data is not normally distributed but data is large enough and t test  robust to normality condition therefore it is valid.