We have been given that a flagpole stands in the middle of a flat, level field. 50 feet away from its base, a surveyor measures the angle to the top of the flagpole as 48 degrees.
We can see from attached photo that flagpole, the surveyor forms a right triangle with respect to ground.
Therefore, the height of the flagpole is approximately 55.53 feet.
Given: n = 20, sample size xbar = 17.5, sample mean s = 3.8, sample standard deiation 99% confidence interval
The degrees of freedom is df = n-1 = 19
We do not know the population standard deviation, so we should determine t* that corresponds to df = 19. From a one-tailed distribution, 99% CI means using a p-value of 0.005. Obtain t* = 2.8609.
The 99% confidence interval is xbar +/- t*(s/√n)
t*(s/√n) = 2.8609*(3.8/√20) = 2.4309 The 99% confidence interval is (17.5 - 2.4309, 17.5 + 2.4309) = (15.069, 19.931)
Answer: The 99% confidence interval is (15.07, 19.93)