Maximum reduction Possible per pass in rolling

Q. A steel plate 50 mm thick is to be rolled to 42 mm in a four high mill having roll diameter 340 mm. The yield stress is 200 MPa. The coefficient of friction, if the given reduction is the maximum reduction possible, is

1. 0.158
2. 0.217
3. 0.312
4. 0.425

Q. A strip of thickness 40 mm is to be rolled to a thickness of 20 mm using a two-high mill having rolls of diameter 200 mm. Coefficient of friction and arc length in mm, respectively are

1. 0.45 and 44.72
2. 0.45 and 38.84
3. 0.39 and 38.84
4. 0.39 and 44.72