"A person is to count 4500 currency notes. Let an denote the number   of notes he counts in the nth
Channel: Doubtnut
Date: 2020-07-05

A person is to count 4500 currency notes. Let an denote the number   of notes he counts in the nth minute. If `a_1=""a_2="". . . . . .""=""a_(10)=""150` and `a_(10),""a_(11),"". . . . . .` are in A.P. with common   difference 2, then the time taken by him to count all notes is (1) 34 minutes   (2) 125 minutes (3) 135   minutes (4) 24 minutes