Chapter 18 - Heat Engines and Refrigerators - Exercises and Problems - Page 549: 3

a)$\eta = 27.27\%$ b)$W = 15 kJ$

We have $Q_1 = 55kJ, Q_2 = 40kJ $ a) Thermal efficiency is given as $ \eta = \frac{Q_1 - Q_2 }{Q_1}$ $ \eta = \frac{55kJ - 40kJ}{55kJ}$ $\eta = 27.27\%$ b) We have $ W=Q_1 -Q_2 = 55kJ -40kJ$ $W = 15 kJ$