MountainMole Foods has decided to use the perfect order measurement approach to track its logistics performance. According to MountainMole, a perfect order is one that (1) is delivered on time, (2) arrives in one complete shipment, (3) arrives undamaged, and (4) is correctly billed. MountainMole has the following performance figures for the past four years.

a. Assuming that there is at most one error per order, calculate performance for each of the four years.

b. If someone was looking to improve MoiuntainMole's logistics performance, one should concentrate on the

\begin{tabular}{lcccc} \hline Year & 2015 & 2016 & 2017 & 2018 \\ \hline Total shipments & 105,000 & 165,000 & 195,000 & 240,000 \\ On-time shipments & 100,000 & 155,000 & 190,000 & 235,000 \\ Complete shipments & 101,500 & 156,000 & 169,000 & 211,500 \\ Undamaged shipments & 103,000 & 163,000 & 194,000 & 238,000 \\ Correctly billed shipments & 65,000 & 119,500 & 158,000 & 193,500 \\ \hline \end{tabular}