Inspection of a random sample of 27 aircraft showed that 16 needed repairs to fix a wiring problem that might compromise safety.

Inspection of a random sample of 27 aircraft showed that 16 needed repairs to fix a wiring problem that might compromise safety. How large a sample would be needed to estimate the true proportion of jets with the wiring problem, with 98 percent confidence and an error of +/- 8 percent.  Please show your work, in particular how I can compute z-value.