a) estimate the mean and the standard deviation of this process?

b)Suppose that parts below the lower specification limits can be reworked, but parts above the upper specification limit must be scrapped. Estimate the proportion of scrap and rework produced by this process.

c)Suppose that the mean of this process can be reset by fairly simple adjustment. What value of the process mean would you recommend?

Estimate the proportion of scrap and rework produced by this process at this new mean.

Please help me :"( I don't get it.