An air conditioning contractor has kept detailed records on the lifetimes of a random sample of...
An air conditioning contractor has kept detailed records on the lifetimes of a random sample of 250 compressors. She plans to use the sample mean lifetime, x, of those 250 compressors as her estimate or he population mea lifetime μ o al such compressors if the e meso this randon compressor avea standard deviation of 30 months, what is the probability that the contractor's estimate will be within 7 months of the true mean? The probability is (Round to four...
An air conditioning contractor has kept detailed records on the lifetimes of a random sample of 300 compressors. She plans to use the sample mean lifetime, x overbar, of those 300 compressors as her estimate for the population mean lifetime, mu, of all such compressors. If the lifetimes of this brand of compressor have a standard deviation of 50 months, what is the probability that the contractor's estimate will be within 5 months of the true mean?
An air conditioning contractor has kept detailed records on the lifetimes of a random sample of 250 compressors. She plans to use the sample mean lifetime, x, of those 250 compressors as her estimate for the population mean lifetime, u, of all such compressors. If the lifetimes of this brand of compressor have a standard deviation of 45 months, what is the probability that the contractor's estimate will be within 7 months of the true mean? The probability is (Round...
1) A consumer advocacy group tested the "on-air" lifetimes of a random sample of 132 1) cell phone batteries. The mean lifetime was 3.8 hours with a standard deviation of 0.4 hours. The lifetimes are approximately bell-shaped. Estimate the number of batteries with lifetimes between 3.0 hours and 4.6 hours. A) almost all (greater than 125) ) 90 D) 7 Z132-3.2