To the nearest pound, Rosie has £12. She wants to buy 6 drinks. Each drink costs £1.89. Show that Rosie definitely has enough money to buy the 6 drinks.

The phrase "to the nearest pound" implies we need to consider the limits of accuracy, or bounds. Rosie has £12 to the nearest pound. This means the actual amount of money she has is between £11.50 (inclusive) and £12.50 (exclusive). To be certain she has enough money, we must check if the minimum possible amount she has is enough to cover the cost. The lower bound of her money is £11.50. Next, we calculate the total cost of the drinks: Cost = 6 drinks × £1.89/drink = £11.34. Finally, we compare her minimum possible money with the cost: £11.50 is greater than £11.34. Since the least amount of money she could possibly have is more than the cost of the drinks, she definitely has enough money.