Answer
See below.
Work Step by Step
The total weight lifted can be calculated by summing the first $5$ terms of the arithmetic sequence with $a_1=100$, $d=30$ multiplied by $10$, since there are $10$ repetitions in each set.
The sum of the first $n$ terms of an arithmetic sequence can be obtained by the following formula: $\frac{n(a_1+a_n)}{2},$ where $a_1$ is the first term, $a_n$ is the nth term and $n$ is the number of terms.
Thus $a_5=100+(5-1)30=220$. Thus $S_5=\frac{5(100+220)}{2}=800$.
We have to multiply this by $10$, thus the total weight lifted is $8000$ pounds.
