Challenge question: Home mortgages use amortization schedules, but the principal balance might be 10 or 100 times larger than Janet's $3500 trip. They're typically paid back over a period of 30 years at a much lower interest rate (^ infty 4\%) . Explain what you think that amortization schedule might look like.

Afactory makes propeller drive shafts for ships. a quality assurance engineer at the factory needs to estimate the true mean length of the shafts. she randomly selects four drive shafts made at the factory, measures their lengths, and finds their sample mean to be 1000 mm. the lengths are known to follow a normal distribution whose standard deviation is 2 mm. calculate a 95% confidence interval for the true mean length of the shafts. input your answers for the margin of error, lower bound, and upper bound.