Question

A monkey climbs 20 feet at the beginning of each hour and rests for a while when he slips back 5 feet before he again starts climbing in the beginning of the next hour. If he begins his ascent at 8:00 AM, at what time will he first touch a flag at 110 feet from the ground?

Accepted Answer

B. Net climb per hour = $20 - 5 = 15$ feet. In 6 hours (from 8:00 AM to 2:00 PM), net climb = $6 	imes 15 = 90$ feet. At the start of the 7th hour (2:00 PM), the monkey climbs 20 feet. Height reached = $90 + 20 = 110$ feet. He touches the flag at 110 feet right at the beginning of the 7th hour, which is 3:00 PM (after 7 hours of ascent cycle start). Hence, Option B is correct.

Monkey Climbing Pole Time

Explanation

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