1. A dishwasher has a mean life of 12 years with an estimated standard deviation of 1.25 years ("Appliance life expectancy," 2013). The life of a dishwasher is normally distributed. Suppose you are a manufacturer and you take a sample of 12 dishwashers that you made. a) State the random variable. b) Find the mean of the sample mean. c) Find the standard deviation of the sample mean. d) Find the probability that the sample mean of the dishwashers is less than 7 years. e) If you found the sample mean life of the 12 dishwashers to be less than 7 years, would you think that you have a problem with the manufacturing process? Why or why not? 2. The Kyoto Protocol was signed in 1997, and required countries to start reducing their carbon emissions. The protocol became enforceable in February 2005. In 2004, the mean CO2 emission was 4.87 metric tons per capita. You wonder if there enough evidence to show that the mean CO2 emission is lower in 2010 than in 2004. a) State the random variable. b) State the population parameter. c) State the null and alternative hypotheses.

Fig: 1