After striking the floor, a certain ball rebounds (4/5)th of height  from which it has fallen. Then the total distance that it travels before coming to rest, If it is gently dropped from a height of 120 m is

Initially the ball falls from a height of 120m. After striking the floor, it rebounds and goes  to a height of 45×120m  Now, it falls from a height of  45×120m and after rebounding goes to a height  of  4545120 m. This process is continued till the ball comes to rest Hence, the total distance travelled is 120+12045+120452+.....=1201-45=600m