Since the average is the sum divided by the count, the sum is the average times the count.
So the sum of the weights of the watermelons is 10(4.3)=43 pounds.
The sum of the weights of the pumpkins are 5(3.4)=17 pounds
The sum of the weight of the fruits is 43+17=60 pounds
Dividing by 15 fruits gives an average item weight of 60/15 = 4 pounds
