Suppose that 60% of a particular electronic part last over 3 years, while 70% last less than 6 years. Assuming a normal distribution, what are the mean and standard deviation with regard to length of life of these parts?
(A)μ = 3.677, σ = 3.561 (B)μ = 3.977, σ = 3.861 (C)μ = 4.177, σ = 3.561 (D)μ = 4.377, σ = 3.261
B