Random Samples of 200 Parts were taken on an assembly line every hour for the past 25 hours. the number of defective parts is shown in the accompanying table:

sample :------1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

# of defective:5 2 4 10 2 6 8 2 0 5 12 11 8 10 5

sample :------16 17 18 19 20 21 22 23 24 25

# of defective:13 7 5 7 11 3 16 3 2 10

What is the estimate of the standard error of the proportion of defective parts?

I used a program to graph the points and found sample 22 out of control. Afterwards i do the calculations of dividing 3sigma by 3 and get a value of 0.012705 but that isn't one of the choices. I used the formula (p*(1-P)) / n too and got the same answer as well. Could it be that i'm using the wrong formula or finding the wrong value?

The options are :

a. 0.0125

b. 0.0251 (i think they have this one listed as correct)

c. 0.0700

d. 0.0002

e. 0.0324