The alkene shown reacts with $\mathrm{HBr}$. Which structure is the major product?

The alkene is vinylcyclohexane. Protonation of the terminal carbon gives a secondary cation next to the ring CH, and a 1,2-hydride shift from the ring carbon gives a tertiary ring cation. The product is 1-bromo-1-ethylcyclohexane.