Given the following for ABC Company, at what weighted average cost of capital (WACC) will ABC Company generate zero residual operating income (ROPI) in 2007?

($ in thousands) 2007, 2006 Net operating assets (NOA), end of year: $9,000 $6,100 Net operating assets (NOA), beginning of year $6,100 $5,650 Net operating profit after tax (NOPAT) $1,375 $1,200 Weighted average cost of capital 8% 8%