Please help :) A sample of 60 Grade 9 students' ages was obtained to estimate the mean age of all Grade 9 students. X = 15.3 years and the population variance is 16.

a. What is the point estimate for μ?

b. Find the 95% confidence interval for μ.

C. Find the 99% confidence interval for μ.

d. What conclusions can you make based on each estimate?

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Apinhole camera is made out of a light-tight box with a piece of film attached to one side and pinhole on the opposite side. the optimum diameter d(in millimeters) of the pinhole can be modeled by d=1.9[ (5.5 x 10^-4) l) ] ^1/2, where l is the length of the camera box (in millimeters). what is the optimum diameter for a pinhole camera if the camera box has a length of 10 centimeters