A research reported on a study of different algorithms for estimating software development costs. Four algorithms were applied to nine software development projects and the percent error in estimating the development cost was observed as below. Use minitab for this problem.The PCR for a measurement is $0\mathrm{.}8$ and the control limits for an $x$ bar chart with subgroup sample

size $n=5$ are $25$ for lower control limit and $30$ for upper control limit$.$

$($a$)$ Estimate the process standard deviation $.(6$ pts$)$

$($b$)$ Assume that the specification limits are centered around the process mean. Find the upper and lower

specification limits$.(8$ pts$)$

$($c$)$ Assume that the specification limits are centered around the process mean. Calculate fraction defective. $(8$ pts$)$