The police chief selects a sample of 49 local police officers from a population of officers with a mean physical fitness rating of 72 ± 7.0 (μ±σ) on a 100-point physical endurance rating scale. He measures a sample mean physical fitness rating on this scale equal to 74. He conducts a one-independent sample z test to determine whether physical endurance increased at a .05 level of significance.

Suppose that a customer is purchasing a car. He conducts an experiment in which he puts 10 gallons of gas in the car and drives it until it runs out of gas. He conducts this experiment 15 times on each car and records the number of miles driven. Range for Car 2 R= 70 mi / 10 gal (Type an integer or decimal rounded to one decimal place as needed.) Full data set Sample standard deviation for Car 1 s= mi / 10 gal (Type an integer or decimal rounded to one decimal place as needed.) Car 1 245 242 215 244 220 265 291 160 284 251 169 319 257 306 267 Sample standard deviation for Car 2 Car 2 s= mi / 10 gal (Type an integer or decimal rounded to one decimal place as needed.) 230 206 214 236 242 256 245 255 241 264 276 252 250 251 257

You want to obtain a sample to estimate a population mean. Based on previous evidence, you believe the population standard deviation is approximately σ=57.4σ=57.4. You would like to be 99% confident that your estimate is within 1.5 of the true population mean. How large of a sample size is required?

You want to obtain a sample to estimate a population mean. Based on previous evidence, you believe the population standard deviation is approximately σ=55.5σ=55.5. You would like to be 99% confident that your estimate is within 5 of the true population mean. How large of a sample size is required?