He has to pay $ 2.76 for the yogurt.
Step-by-step explanation:
Given data
Cost of each ounce = $ 0.24
Vanilla yogurt = 6.5 ounces
Strawberry yogurt = 5 ounces
Total ounces = 6.5 + 5 = 11.5 ounces
Now Total cost of yogurt = 11.5 × 0.24
Now Total cost of yogurt = $ 2.76
Therefore he has to pay $ 2.76 for the yogurt.