292 293 294 295 296 297 298 19. A student records the repair costs for 20 randomly selected computers from a local repair shop where he works. A 299 sample mean of $216 53 and standard deviation of $15.86 were calculated. Construct a 98% confidence interval to 300 estimate the population mean repair cost for all computers repaired at the local shop. Then, report your findings injan 301 interpretive sentence. 302 303 304 305 306 307 308 309 310 20. Redo #19, only this time assume the value $15.86 is the population standard deviation. Then, state this interval below 311 within an interpretive sentence tied to the given context. 312 313 314 315 316 317 318 319 320 21. For a psychology experiment, Juana is assigned the task of finding the average number of hours U.S. college students 321 sleep each night. Her results must be at the 90% level of confidence with a maximum margin of error of 0.2 hour. 322 Assuming the standard deviation is 1.8 hours (based on a previous, reliable study), what is the minimum number of 323 students Juana must survey? 324 325 326 327