A recycling compactor compresses material in two stages. The energy transferred to compressing the material is useful.
| Stage | Duration in s | Input power in kW |
|---|---|---|
| initial compression | 40 | 1.5 |
| final compression | 60 | 0.80 |
The efficiency of the initial compression stage is 0.80.
During the final compression stage, 18 kJ of energy is dissipated.
Calculate the overall efficiency of the compactor for both stages. Give your answer as a percentage.