STA 205 Lab 4: Confidence Interval for the Proportion Name: ata on the apps down
ID: 3306508 • Letter: S
Question
STA 205 Lab 4: Confidence Interval for the Proportion Name: ata on the apps downloaded to the smartphones of American millennials (adults between the ages of 18 & 34). Respondents were asked In a sample of 625 American millennials, 205 had downloaded Snapchat. which apps they had downloaded to their phone. a. What variable is recorded for each individual sampled? Classify the variable as categorical or quantitative. Estimate the proportion of all American millennials who have downloaded Snapchat onto their smartphone with 99% confidence. (Round decimal calculations to four decimal places) b. According to the same survey, it was estimated with 99% confidence that between 19.41% and 28.19% of millennials have Twitter installed on their phone. Based on this interval and the one calculated in part b, can we conclude that the proportions of millennials with this two apps installed differ? Explain c. your answer.Explanation / Answer
a) variable recorded the name of apps they had downloaded for their phone
this is categorical variable (cause counting( frequuency is inolved in it)
b)here sample proportion phat=205/625= 0.328
std error =(phat*(1-phat)/n)1/2 =0.0188
for 99% CI ; z=2.5758
therefore 99% confidence interval for proportion who download snapchat =phat -/+ z*std error
=0.328 -/+2.5758*0.0188 =0.2796 to 0.3764 ~ 27.96 % to 37.64%
c)as interval for twitter as well that for snapchat contains some common values therefore we can not conclude that proportion of these differ,
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