Question: Researchers have established that the population standard deviation (a) for body weight for 20-29 year-old US males is 40 pounds.

i) How many observations (sample size) do we need in order to estimate mean body weight (p.) with 95% confidence and a margin of error of ±10 pounds?

ii) How many observations (sample size) do we need in order to estimate mean body weight (p) with 95% confidence and a margin of error of ±5 pounds?

iii) How many observations (sample size) do we need in order to estimate mean body weight (p) with 95% confidence and a margin of error of ±1 pound?