Project X Stage Total Cost Total Benefit Marginal Cost Marginal Benefit Net Marginal Benefit Net Total Benefit 1 $3,000 $6,000 $3,000 $6,000 $3,000 $3,000 2 $8,000 $15,000 $5,000 $9,000 $4,000 $7,000 3 $12,000 $21,000 $4,000 $6,000 $2,000 $9,000 Project Z Stage Total Cost Total Benefit Marginal Cost Marginal Benefit Net Marginal Benefit Net Total Benefit 1 $4,000 $6,000 $4,000 $6,000 $2,000 $2,000 2 $8,000 $14,000 $4,000 $8,000 $4,000 $6,000 3 $12,000 $21,000 $4,000 $7,000 $3,000 $9,000 Based on the table above, which stages of X and Z should be chosen if $12,000 is available; if $20,000 is available