Beth gave the cashier $20 to pay for 3 pairs of socks. The cashier gave her $11.03 in change. Each pair of socks cost the same amount.

To find the cost of each pair of socks, we first need to determine the total amount Beth spent.

Beth gave the cashier $20 and received $11.03 in change. Therefore, the amount Beth spent can be calculated as follows:

\[ \text{Amount spent} = \text{Amount given} - \text{Change received} = 20.00 - 11.03 = 8.97 \]

Now, Beth spent $8.97 for 3 pairs of socks. To find the cost of each pair of socks, we divide the total amount spent by the number of pairs:

\[ \text{Cost per pair} = \frac{\text{Total amount spent}}{\text{Number of pairs}} = \frac{8.97}{3} \]

Calculating that gives:

\[ \text{Cost per pair} = 2.99 \]

Thus, the cost of each pair of socks is $2.99.