Exp. (b)
The integer greater than 6000 may be of 4 digit or 5 digit. So, here two cases arise.
Case I When number is of 4 digit. Four digit number can starts from 6,7 or 8
Thus, total number of 4 digit number, which are greater than 6000=3×4×3×2=72
Case II When number is of 5 digit. Total number of five digit number which are greater than 6000=5 ! =120
∴ Total number of integers =72+120=192