Final answer:
Kristina needs to buy at least 2 bottles of wine for her dinner party.
Step-by-step explanation:
To determine how many 750 ml bottles of wine Kristina needs to buy, we can first convert the 8 ounces of wine per guest into milliliters.
Since 1 ounce is approximately 29.5735 milliliters, 8 ounces would be approximately 236.588 ml.
Then, we divide the total volume of wine needed (6 guests x 236.588 ml per guest) by the volume of each bottle (750 ml) to find the number of bottles needed.
Therefore, Kristina needs to buy approximately 1.594 bottles of wine, but since she can't buy a fraction of a bottle, she would need to buy at least 2 bottles to make sure each guest gets 8 ounces of wine.