"How much is senior discount on Carnival Cruise" is a noun phrase that describes the amount of discount offered to senior citizens by Carnival Cruise. For example, a senior citizen might ask, "How much is the senior discount on the upcoming Carnival cruise to the Caribbean?"
Knowing the cost of senior discounts can be personally important, as it is financially beneficial for the senior population. Historically, senior citizen discounts have increased in popularity dating back to the 1950s, when rail passes and airline tickets initially offered reduced rates.