Alarge asteroid crashed into a moon of another planet, causing several boulders from the moon to be propelled into space toward the planet. astronomers were able to measure the speed of one of the projectiles. the distance (in feet) that the projectile traveled each second, starting with the first second, was given by the arithmetic progression 20, 60, 100, 140, …. find the distance that the projectile traveled in the 9th second.