Sequences & Series · JEE Main previous year questions

2010 1 question

1. Q52010 · 25 Apr 2010 · Shift 1

   A person is to count 4500 currency notes. Let $a_n$ denote the number of notes he counts in the $n^{th}$ minute. If $a_1=a_2=\cdots =a_{10}=150$ and $a_{10},a_{11},\dots$ are in an AP with common difference - 2, then the time taken by him to count all notes is

   1. A.$34\mathrm{minutes}$
   2. B.$125\mathrm{minutes}$
   3. C.$135\mathrm{minutes}$
   4. D.$24\mathrm{minutes}$
   Show answer

   Answer: A