Question

Assume that we want to construct a confidence interval. Do one of the following, as appropriate: (a) find the critical value tu/2, (b) find the critical value Za/2, or (c) state that neither the normal distribution nor the t distribution applies. Here are summary statistics for randomly selected weights of newborn girls: n=254, = 31.7 hg, s= 6.3 hg. The confidence level is 90%. Select the correct choice below and, if necessary, fill in the answer box to complete your choice. O A. ta/2 (Round to two decimal places as needed.) OB. Za/2= (Round to two decimal places as needed.) O C. Neither the normal distribution nor the t distribution applies.

Answer 1

solution:-

given that n = 254 , x = 31.7 , s = 6.3

degree of freedom df = n - 1 = 254 - 1 = 253

we look into t-distribution table with df = 253 and with two tailed 90% confidence level

A. tα/2 = 1.65