please help me with this problem!!

Question

Software testers have reported their testing results of your team’s latest software release. Out of a sample of 1540 tests, 117 tests resulted in a crash. Your boss wants an estimate of the true proportion of software crashes based on this information using a 95% level of confidence. Construct a confidence interval for the proportion of sessions that result in a crash.

The lower limit of the interval is?

The upper limit of the interval is?

Answer 1

CI = phat +/- z-critical * sqrt(phat * (1-phat)/sample size)

here phat = 117/1540

z-critical = 1.96

sample size = 1540