What is the confidence level for the interval x 2.880/n? (Round your answer to one decimal place.) % (b) What is the confidence level for the interval x 1.470/n? (Round your answer to one decimal place.) (c) What value of z % a/2 in the CI formula below results in a confidence level of 99.7%? (Round your answer to two decimal places.) Za/2" = x + z /2 ) Z/2 n (d) Answer the question posed in part (c) for a confidence level of 66%. (Round your answer to two decimal places.) Za/2 a/2 =