Question

You observe 40 customers at a coffee shop, and 77% of them tip. What is the 95% confidence interval for the proportion of customers that tip?

Group of answer choices

(0.010, 0.951)

(0.640, 0.900)

(0.703, 0.837)

(0.661, 0.879)

Answer 1

area:0.025, mean:0, SD:1 gives z= -1.960 or z* = 1.960

Now, 95% confidence interval using the data

z*((1-) / n) = 0.77 196(0.77(1-0.77) / 40)
= 0.77.13042
= (.90042 , .6395) ... option b
where is the point estimate