Chapter 12 Sequences and Series - 12.2 Analyze Arithmetic Sequences and Series - 12.2 Exercises - Problem Solving - Page 809: 68c

$3750; 13123.5 \pi$

From part (b), we have $l_n=2 \pi + (n-1) 0.0008 \pi$ or, $5=2 \pi + (n-1) 0.0008 \pi$ Thus, $n=3750$ The arithmetic sum of the $l_n$ terms is: $1.9992 \pi n +0.0008 \pi \sum _{i=1}^ ni=1.9992 \pi n +0.0004 \pi (n+1)$ Hence, we have $3750; 13123.5 \pi$