Question 871995
Ho: u = 45 (claim)
Ha: u < 45
 t = -1.25/4/sqrt(36) = -1.875    
P(t < 1.874) = .0346 0r 3.46%     DF(35)
a) Using the 2.5% significance level, would you conclude 
that the mean life is less 45 months. NO. 3.46% is not less than 2.5%
 b) Using the 5% significance level, would you conclude 
that the mean life of the batteries is less 45 months? YES.  3.46% < 5%