3. Consider an engineered object put in service at time 0 with time to failure following a Weibull distribution - having CDF F(t)=1-e where 0 = 800 hours and B = 3. a. What is the probability that the object complete a mission of length 400 hours? [4] b. How many failures do you expect to occur during 500 hours from the start? [4] c. How many spare parts will be needed over a period of 5000 hours if this object is replaced periodically every 500 hours? [4] d. How many spare parts will be needed over a period of 5000 hours if this object is replaced preventively at age 400 hours or at failure whichever occurs first? (No calculation needed simply write the formula) [4] e. How many spare parts will be needed over a period of 5000 if this object is run to failure? [4]