Answer:
1. Rate of Interest = Net operating expenses/Average operating assets
Osaka = $210000/$1000000 = 0.21 = 21%
Yokohama = $720000 / $4000000 = 0.18 = 18%
2. Osaka Yokohama
Average operating assets $1,000,000 $4,000,000
M. required return at 15% $150,000 $600,000
Net operating income $210,000 $720,000
Minimum required return $150,000 $600,000
Residual income $60,000 $120,000