A frog fell into a 20 metre deep well each day, it managed to climb a 3 metres, but the same night, it would slip back 2 metres. How many days did
it take to get out of the well?
Answers
Answer:
Step-by-step explanation:
It is given that the distance climbed by the frog during daytime=3m
The distance by which the frog falls during night=2m
Therefore,
the effective distance covered by the frog in a day
=the distance climbed by the frog during daytime - The distance by which the frog falls during night
=3m-2m=1m
Thus, effectively the frog takes one day to climb one meter. Therefore, it should take 27×1 days to climb up 27m……………………(1.1)
However, on the 28th day, once the frog climbs up 3m in the daytime, it will get out of the well……….(1.2)
Therefore, from (1.1) and (1.2), we see that the number of days required for the frog to get out of the well = Time taken to climb 27m+ 1day to ascend 3m during daytime
=27days+1 day=28days
Thus, the required answer is 28 days.
Note: We should not consider that the effective length travelled by the frog on all days is 1m because it just needs to reach the top of the well, which it does on the daytime of 28th day. Therefore, after the 28th day’s daytime, we should not consider that it would fall 2m again at night as it would have already gone out.