Well the recipe is for 4 people and you want to make it for 10 .... or 10/4 = 2 1/2 times as many people ...so multiply each of the ingredients by 2 1/2 (or 2.5)(or 5/2)
OJ 1/2 cup x 2.5 = 1/2 x 5/2 = 5/4 = 1 1/4 cups
Pineappple 1 cup x 2 1/2 = 2 1/2 cups
syrup 1/3 cup x 5/2 = 5/6 = 1 1/6 cups