A quality analyst wants to construct a control chart for determining whether four machines, all producing the same product, are in control with regard to a particular quality attribute. Accordingly, she inspected 1,000 units of output from each machine in random samples, with the following results

Machine	Total Defectives
#1	23
#2	15
#3	29
#4	13

What is the estimate of the process proportion of defectives?

Multiple Choice

.08

.06

.04

.01

.02