Suppose data collected by observers at randomly selected intersections across the country revealed that in a sample of 400 drivers, 380 were using their cell phone.
a. Give a point estimate of it, the true driver cell phone use rate (that is, the true proportion-or-population porportion- of drivers who are using their cell phone while driving).
b. Compute a 95% confidence interval for it.
c. Give a practical interpretation of the interval, part b.