For a p chart, the standard deviation of the proportions is 0.079057.The number of items in each sample is 30.Then p is ______.
A)There is not enough information to determine p
B)0.25
C)0.33
D)0.45
E)0.48

Question

Quizplus · Accepted Answer

The standard deviation of the proportions in a p chart is calculated using the formula $\sqrt{\frac{p(1-p)}{n}}$, where $p$ is the proportion of defectives, and $n$ is the number of items in each sample. Given the standard deviation is 0.079057 and $n = 30$, we can solve for $p$. Rearranging the formula to solve for $p$, we get $p(1-p) = (0.079057)^2 \times 30$. Solving this quadratic equation, we find that $p = 0.25$ is the valid solution within the range of 0 to 1 for a proportion.

For a P Chart, the Standard Deviation of the Proportions