An insect climbs up 2 cm up a slippery rod in one second and slips donw by 1 cm over the next second. How many seconds wll the insect take to reach the top of the rod 15 cm high?
Time taken by the insect to climb 2cm = 1 second
Time taken by the insect to slip 1cm = 1 second
Hence, it climbs 1cm in 2 seconds
Height of the rod = 15 cm
Therefore, time required = 15 x 2
= 30 seconds
Hence, the insect needs 30 seconds to climb the rod.