Question

An operator wants to determine the standard deviation for a machine she operates. To do this, she wants to create a p-chart. Over a month's time, she collects 30 samples of 75 observations each and records the number of errors. The average proportion defective is found to be 0.024. Which of the following is the standard deviation () of the machine?a. Less than or equal to 0.1b. More than 0.1 but less than or equal to 0.5c. More than 0.5 but less than or equal to 1.0d. More than 1.0

Answer 1

The answer is letter A.

Step-by-step explanation:

Less than or equal to 0.1

Because:

Average proportion (P-bar)= 0.024

Observations (n)= 75

sd =√(P-bar)(1-(P-bar)/n

sd =√(0.024)(1-0.024)/75

sd= √(0.024)(0.976)/75

sd= √(0.023424)/75

sd= 0.01767

sd ≤ 0.1