Ps. Use the 5 steps for hypothesis testing

A. A manufacturer of a certain brand of wristwatch claims that the mean life expectancy of the battery of the watch is 48 months. A researcher wants to validate this claim so he chose a sample of 64 watches and noted that their mean life expectancy is 45 months with a standards deviation of 2 months. At , can you conclude that the mean life expectancy is less than 48 months? B. In a certain city, a researcher wishes to determine whether the average income of residents is P13, 000. Using a sample of 22 residents, he found a mean income of P13 565.25 with a standard deviation of P2500. At , can the researcher conclude that the average income of the population is indeed P13 000