The total number of guests expected at the party = 180 guests
Since each guest is given 1 serving, the total number of servings of juice required = 180 servings
Each bottle of juice satisfies 16 servings
Therefore, number of bottles of juice required = Total number of servings at the party/ number of servings per bottle of juice
Therefore, number of bottles of juice required = 180/16 = 11.25 bottles of juice
Since we cannot have a fractional bottle of juice, we round 11.25 as 12 bottles of juice
Number of bottles of juice needed = 12 bottles