Final answer:
The firm charges its customers $34.10 and marks up its price over the marginal cost by a factor of 0.62.
Step-by-step explanation:
The firm's price can be calculated by multiplying the Lerner index with the marginal cost. In this case, the price is 0.62 * $55 = $34.1.
To find the markup factor, we can divide the price by the marginal cost. In this case, the markup factor is $34.1 / $55 = 0.62. This means that the firm marks up its price over the marginal cost by a factor of 0.62.