Learn French: La probabilité de gagner le gros lot est très basse. - The probability of winning the grand prize is very low.

When a noun is followed by an infinitive to explain or define its content, French usually connects them with the preposition de. Here, de links the noun la probabilité to the action gagner.

What exactly does le gros lot refer to?

Le gros lot literally translates to the big share or the big prize. It is the standard French phrase for the jackpot in a lottery or the grand prize in a contest. Just like in English, it can also be used figuratively to mean hitting the jackpot.

Could I use faible instead of basse to describe the probability?

Yes, and it is actually more natural. While basse is correct and widely understood here, native French speakers more frequently use the adjective faible (weak) when describing chances, rates, or probabilities. You will very often hear la probabilité est très faible.

Is there a rule for remembering that probabilité is feminine so we know to use basse?