PARTS A) and B) are unrelated. All are compulsory.

PART A: A researcher wants to estimate the mean daily number of calls that a person makes on a mobile phone. They took a random sample of 16 mobile phone users and found a sample mean of 8 phone calls per day. Assume the population standard deviation is known to be 0.4 phone calls per day. Do NOT check conditions.

i)Construct a 95% confidence interval. SHOW BASIC WORKINGS.

ii)Interpret your confidence interval.

PART B: If = 0.4 and p = 0.2, and n = 30, find the corresponding Z value using the relevant formula