The initial cargo access doors for Boeing's 787 took 400 hours of labor to produce. The learning rate is 80%. How long will the twentieth door take? a. 170 b. 153 C. 320 d. 160 The initial cargo access doors for Boeing's 787 took 400 hours of labor to produce. The learning rate is 80%. How long will the twentieth door take? a. 170 b. 153 C. 320 d. 160