Question

A monkey standing on the ground wants to climb to the top of the vertical pole of $13$ in tall. He climbs $5$ in in $1$ sec and then slips downwards$3$ in in the next second. He again climbs $5$ in. in $1$ sec. and slips by $3$ in. in the next second and so on. How much time will the monkey take to reach the top of the pole?

• A. $7sec.$
• B. $9sec$.
• C. $11sec.$
• D. $13sec.$

Answer 1

The correct option is C $11sec.$

The monkey climbs $5in$ in one second and slips downwards $3in$ in next second

So the monkey is effectively climbing $2in$ in $2sec$

After 10 seconds of climbing and slipping, the Monkey would reach a height of 10 m. On the 11th second the Monkey will climb the remaining $3in$.

So it will take the Monkey $11seconds$ to climb the pole

Hence, Option C is correct.