Multiple choice

A monkey climbs 30 feet at the beginning of each hour and rests for a while when he slips back 20 feet before he again starts climbing in the beginning of the next hour. If he begins his ascent at 8.00 a.m. at what time will he touch a flag which is 120 feet from the ground?

  1. 4 p.m.

  2. 5 p.m.

  3. 6 p.m.

  4. None of these

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Net climb per hour = 30 - 20 = 10 ft. After 9 hours (8am to 5pm), monkey reaches 90 ft. At 5pm, starts at 90 ft, climbs 30 ft to reach 120 ft exactly. No slip back occurs because goal is reached during the climb.