An hourglass consists of two sets of congruent composite figures on either end. corporation each cone of the hourglass has a height of 18 millimeters. the total height of the sand within the top portion of the hourglass is 54 millimeters. the radius of both cylinder and cone is 8 millimeters. sand drips from the top of the hourglass to the bottom at a rate of 10π cubic millimeters per second. how many seconds will it take until all of the sand has dripped to the bottom of the hourglass? 68.3 38.4 268.8 230.4