Here is the practice question:
..standard deviation associated with the product variation was 0.7 inches and with the measurement variation was 0.5 inches, What is the total standard deviation here?
a. 1.2
b. 0.86
c. 0 .49
d.0.25
the answer was b . 0.86. I have no idea how to get to this number. I was looking at the standard deviation formula: P - O/ 6 = standard deviation. Answer states to use variation formula [P -O/6 ]2. I cannot tell what the Pessimistic is or the Optimistic is in this question? Can you please help me?