Dover Enterprises recently used 18,000 labor hours to produce 6,500 completed units. According to manufacturing specifications, each unit is anticipated to take two hours to complete. The company's actual payroll cost amounted to $203,400. If the standard labor cost per hour is $11.1, Dover's labor rate variance is (Do not round intermediate calculations.):

$3,600U.

$3,600F.

$3,700U.

$3,700F.

None of these.