Over half of all American teens (ages 12 to 17 years) have an online profile, mainly on Facebook. A random sample of 511 teens with profiles found that 327 included photos of themselves. 

(a) Give the 96% large-sample confidence interval for the proportion p of all teens with profiles who include photos of themselves. 

Large-sample Interval:  to 

(b) Give the plus four 96% confidence interval for p . (The plus-four interval always pulls the results away from 0% or 100%, whichever is closer. Even though the condition for using the large-sample interval is met, the plus four interval is more trustworthy.) 

Plus four Interval: