How fast u can climb the well!
Level
pending
A man accidentally fell in a 30 metres well and stayed alive. His friend gave him a rope. The man was able to climb 3 metres, but slipped back 1.5 metres in 5 minutes. How much time will he take to climb up the well?
105
90<t<95
100
100<t<105
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1 solution
So, by our calculation we get that in 5 min the gain is 3-1.5 = 1.5 metres. Now it is not mentioned how much time he climbs and how much time he slips so the inequality is brought here.
At the 90th minute he has moved 1.5 x 18 = 27 minutes. Now, this is crucial. As soon as he reaches the top he wont slip. He will escape. So, he take 90+x time to escape where 0<x<5.
So, he will climb out of the well in 90<t<95 minutes and not 100.