Question

A new president at Liberty University has made student satisfaction with the enrollment and registration process one of her highest priorities. Students must see an advisor, sign up for classes, obtain a parking permit, pay tuition and fees, and buy textbooks and other supplies., During one registration period, 10 students every hour are sampled and asked about satisfaction with each of these areas. Twelve different groups of students were sampled, and the number in each group who had at least one complaint is as follows: 0, 2, 1, 0, 0, 1, 3, 0, 1, 2, 2, 0

Develop upper and lower control chart limits at the 99% confidence level for the proportion of students with complaints. Does the enrollment and registration process appear to be in control?

Answer 1

Average complaint rate = total number of defects/(no of samples*sample size) = 12/(12*10) = 0.1 = p-bar

Sp = sqrt((p-bar*(1-p-bar))/sample size) = sqrt((0.1*(1-0.1))/10) = 0.09486833

UCL = p-bar + z*Sp = 0.1+3*0.09486833 [for 99.73% confidence level, z = 3] = 0.38460499

LCL = p-bar - z*Sp = 0.1-3*0.09486833 = -0.18460499 = 0 (Adjusted)

yes the enrollment appears to be in control