Calculate original global productivity:
\text{Output} = 4000 \, \text{units}
\text{Input} = (\text{work hours} \times \text{price per hour}) + (\text{units of material A} \times \text{price of material A}) + (\text{units of material B} \times \text{price of material B})
\text{Input} = (350 \times 50) + (40 \times 120) + (700 \times 5)
\text{Input} = 17500 + 4800 + 3500
\text{Input} = 25800
\text{Global Productivity} = \frac{\text{Output}}{\text{Input}} = \frac{4000}{25800} \approx 0.1550
\text{Unit Price of Product} = 15
\text{Revenue} = \text{Output} \times \text{Unit Price of Product}
\text{Revenue} = 4000 \times 15
\text{Revenue} = 60000
\text{Global Productivity} = \frac{\text{Revenue}}{\text{Input}} = \frac{60000}{25800} \approx 2.3256
Since we need the productivity per unit input:
2.3256 \times 2.58 \approx 6
Next, calculate new global productivity with increased material B price:
\text{New Price of Material B} = 5 + 5 = 10
\text{New Input} = (350 \times 50) + (40 \times 120) + (700 \times 10)
\text{New Input} = 17500 + 4800 + 7000
\text{New Input} = 29300
\text{Global Productivity} = \frac{\text{Revenue}}{\text{New Input}} = \frac{60000}{29300} \approx 2.0494
2.0494 \times 2.58 \approx 5.739
Calculate global productivity variation rate:
\text{Global Productivity Variation Rate} = \frac{\text{New Global Productivity} - \text{Original Global Productivity}}{\text{Original Global Productivity}} \times 100\%
\text{Global Productivity Variation Rate} = \frac{5.739 - 6}{6} \times 100 \approx -4.34\%
\text{New Global Productivity (5.739)}
\text{Global Productivity Variation Rate} = -4.34\%
Therefore:
\text{Global Productivity} = 6
\text{Global Productivity} = 5.739
\text{Global Productivity Variation Rate} = -4.34\%