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. $0.45\:\text{and}\:38.84$
2. $0.39\:\text{and}\:38.84$
3. $0.39\:\text{and}\:44.72$
4. $0.45\:\text{and}\:44.72$