Question

A person is to count 4500 currency notes. Let an denote the number of notes he counts

Answer 1

i m unable to understand your question.

Answer 2

suppose he takes n minutes to count 4500 notes.
If a1 = a 2 = .... = a 10 = 150
then a1+a2+........+a10=1500
hence a11+a12+.....+an=3000
\frac{n-10}{2}(a11+an)=3000
\frac{n-10}{2}(148+148+(n-11)(-2))=3000
n2-169n+4590=0
n=135,34
so all the notes get counted in 34 minutes....

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