In a certain region, the earth's magnetic field has a magnitudeof 5.1 x 10-5 T and is directed north at an angle of64° below the horizontal. An electrically charged bullet isfired north and 13° above the horizontal, with a speed of 630m/s. The magnetic force on the bullet is 3.6 x 10-10 N,directed due east. Determine the bullet's electric charge,including its algebraic sign (+ or -).