(a)Concentration of free electrons is 5.902e+012 cm^-3
(b)Concentration of holes is 1.059e+014 cm^-3
since p_0>n_0 the sample is p-type
When N_A=N_D=10^15,
 n_0=p_0 from the neutrality equation
Thus the germanium sample in this question is intrinsic by compensationWhen N_D=10^16,
(c)p_0=6.25e+010 cm^-3
Since n_0>p_0,germanium sample in this case is n-type