To calculate the total cost of the tomatoes, you can multiply the weight of the tomatoes by the price per pound.
Hannah bought 3.8 pounds of tomatoes at $1.45 per pound, so the calculation is:
\[ \text{Total cost} = \text{Weight} \times \text{Price per pound} = 3.8 , \text{pounds} \times 1.45 , \text{dollars/pound} \]
Now performing the multiplication:
\[ 3.8 \times 1.45 = 5.51 \]
Thus, Hannah paid $5.51 for the tomatoes.