Alabama Instruments Company Has Set Up a Production Line to Manufacture

Short Answer

Alabama Instruments Company has set up a production line to manufacture a new calculator. The rate of production of these calculators after $t$ weeks is
$$\frac { d x } { d t } = 5700 \left( 1 - \frac { 130 } { ( t + 18 ) ^ { 2 } } \right)$$
calculators per week. Production approaches 5,700 per week as time goes on, but the initial production is lower because of the workers' unfamiliarity with the new techniques. Find the number of calculators produced from the beginning of the third week to the end of the fourth week.
Round the answer to the nearest integer.