Could someone please solve this question?

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To find the maximum number of cards that must be drawn to ensure that 3 cards of the same suit have been drawn, let’s analyze the worst-case scenario.

Since 5 cards have already been drawn, we need to draw more cards to ensure we have at least 3 cards of the same suit.

In the worst-case scenario, let’s assume that we continue drawing cards such that with each new card drawn there would be two cards of the same suit. This means we would draw two cards of hearts and one card of diamonds, so that in the end we have 2 diamonds, 2 spades, 2 clubs and 2 hearts. To ensure we have at least 3 cards of the same suit, we would need to draw one last additional card.

Therefore, the maximum number of cards that must be drawn from the deck to ensure that 3 cards of the same suit have been drawn is 2 hearts+1 diamonds+1 card from any of the four suits=4.