Major product in nitration
Read this first: Why methyl group is 2,4-directing?

From that answer, we understand that methyl groups (or alkyl groups in general) are o/p directing because of hyperconjugation, and not inductive effects! In fact, as you may also know, inductive effects are generally overshadowed by hyperconjugative effects.

The aromatic ring on the left is more activated because it has two alpha hydrogens - implying more number of hyperconjugative structures - as opposed to only one for the right aromatic ring (a small difference, but good enough for elementary level questions). Thus nitration takes place at the para position of the left ring.