I think that they are trying to get you to look at this as an SN1 reaction. So for the mechanism see
When the CH3(CH2)2(CH2)+ species is genreated there are a number of possible outcomes. It is not the most stable carbocation that can be formed so it could form a more stable secondary carbocation by migration of an H from C-2 to C-1 to give
CH3(CH2)(CH)+CH3. The carbon chain could also rearrange to give a tertiary carbocation which is more stable.
A competing side reaction
could be elimination to give
similarly the secondary carbocation could form either of the alkenes
The ratio of the various possible products will depend on the conditions.