What was the fund's overall return, weighted by holding size?

Weight each group's value by its size: Σ(size × value) ÷ Σ(size). A simple mean of the group values is the classic error. The correct answer is 5.0%. Traps to avoid: 13.0% comes from the "summed returns" error; 4.3% comes from the "unweighted mean" error; 6.0% comes from the "dropped a group" error; 4.0% comes from the "median not mean" error.