Question

Q31. In climbing a 21 metre long round pole, a monkey climbs 6 metres in the first minute and slips 3 metres in the next minute. How many minutes would the monkey take to reach the top of the pole?

• A. (a) 11
• B. (b) 14
• C. (c) $14\frac{2}{3}$
• D. (d) 9

Answer 1

The correct option is A

(a) 11

In this type of problem you need first to be sure what constitutes a cycle of movement. Here a cycle constitutes going up 6 metres and slipping by 3 metres. In effect in a cycle of 2 minutes the monkey goes up by 3 metres.

Then you need to consider the way the game would end. When the monkey reaches at the top, it would not slip.

The monkey would complete five cycles to reach 15 metres. From there in 1 minute it would reach the top. Thus, the game would end in 11 minutes.