7. Quality-control studies for Speedy Jet computer printers show that the lifetime of the printer follows a normal distribution with mean p = 4 years and standard deviation o = 0.76 years. The company will replace any printer that fails during the guarantee period. How long should Speedy Jet printers be guaranteed if the company wishes to replace no more than 12% of the printers? (HINT: Inverse normal distribution) boblyon may X= Z = de neril mor piew lllw. natlol blondsew-Of vritiger s isrit viilidsdong art al tenW Seeonuo 19 =