Answer:
It will take approximately 41.68 hours for 1/4 million species of beetles to embark onto the ark once the first pair starts up the gangplank.
Explanation:
The length of the column will be [tex]250000\times 6[/tex]cm (if there's 5 cm between them, not 5 cm from center to center, that wasn't clarified)
L = 1500000 cm
At 10 cm/sec, it will take 150000 seconds to pass the bottom of the gang-plank + [tex]\frac{500}{10}[/tex] seconds for them to go up the gang-plank.
150050 seconds total
t = [tex]\frac{15005}{6}[/tex]minutes
t =[tex]\frac{3001}{72}[/tex] hours
t =~ 41.68 hours
Since, it will take approximately 41.68 hours for 1/4 million species of beetles to embark onto the ark once the first pair starts up the gangplank.
