Question

A monkey starts climbing up a tree 20 ft. Tall. Each hour, it hops 3ft. And slips back 2 ft. How much time would it take the monkey to reach the top?

Answer 1

After 2 hours it will climb (3-2)=1ft. The time is {(20-3)÷1+1}hour={17+1}hour=18hour.

Answer 2

Given :

Total height of tree = 20 ft

Each hour, it hops 3 ft. and slips back 2 ft  

To Find :

The number of hours does monkey take to reach the top

Solution :

Monkey when reach total of 17 ft , it will stop slipping for last 3 feet

As in an hour the monkey climbs 3 ft and slips 2 ft

So, Total distance the monkey climbs in an hour = 3 ft - 2 ft = 1 ft

i.e  1 ft is cover in 1 hours

So,  17 ft will be cover in  17 hours

Again ,

At the last 3 ft the monkey climbs, it reaches the top and doesn’t slip back.

So, For last 3 ft to climb, Time taken by monkey = 1 more hour

∴ Total time taken to climb = Time taken in 17 ft + time taken in 3 ft

                                            = 17 hours + 1 hour

                                            = 18 hours

Hence, The Total time taken to climb the top of 20 ft tree is 18 hours  Answer