Interview Trap Riddle : Hungry Worm & Old Tree

A very hungry worm reaches a tree covered in a lot of leaves. The worm eats 1 leaf and goes away.

On the next day... i.e. day 2..., the worm reaches the tree again and this time it eats twice the number of leaves it ate on the previous day... so it eats 2 leaves on the 2nd day...
On day 3, it eats 4 leaves....
On day 4.. it eats 8 leaves...
and so on..

On Day 30.... it eats the corresponding number of leaves for this day.
And all the leaves on the tree are finished on this day.

RIDDLE :
On which day did the worm finish exactly half of the total number of leaves ?

This riddle has a great analogy to a popular 'Lotus in a pond' riddle. But you should be alert while solving this riddle becuase it has a very tricky answer.
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You are most welcome to share puzzle, math problems or any topics for upcoming videos.

[matm]

Very nice problem howerver your explanation of the difference with the lotus in the pond riddle is false : the point is not that the lotus has an initial lenght, the point is that his lenght is equal to 2^n on the day n. The amount of leaves eaten is equal to 2^0 + 2^1 + ... + 2^n on day n. Thats why these two problems are different

[OrenLikes]

Nice! Plus the worm disguises itself as a beetle, lady bug, very well!!!

[maximedition]

Just one question.







Why does the worm keep magically transforming into a ladybug?

[BryanWLepore]

The video works well without music. - well done.

[ashisharma]

Little bit confused with complicated explanation towards the end and comparison between puzzles. Simply what you need to assess is whether problem needs cumulative sum or not. This one does and other pond one doesn’t.

[MdArfin-flfv]

Love your channel for... this type of questions.
Thank you.
👍👍

[afreenm]

I didn't know about lotus in a pond riddle but still got 29

[Epoch]

How come you have a ladybug pictured, but you call it a worm?

[nandapeela]

Actually, I thought Soo deeply for about 5 minutes
And verified in Google for the formulae of geometric progression pausing the video...
Really amazing question
Love your channel and explanation..

[yohankurniawan]

me at first: "oh i finally found Ammar riddle that i've seen before." me later: "wait. damnit"

[vishalmaske]

You are right....I got successfully trapped in Lotus the best thing is that you compared both puzzles at last and cleared my

[MycoCane]

But this assumes that the number of leaves on the tree was exactly 2^30, right? Which we aren't told?

[ciawest]

dam, totally fell in the trap. i should have thought about it abit longer. knowing your riddles are never that simple

[OrenLikes]

Ammar, the worm looks like a ladybug... :)

[天道信じ]

Yeah I got it right, i spent at least 5 minutes to just have a deep thinking of this great question.

[yemesvee]

Good one. I am also trapped. Please keep it up.

[kenhaley]

It's a trap all right. That's not a worm; it's a ladybug!

[mohammedzubair]

Nice riddle, however I am not satisfied with the comparison between the two riddles.

In lotus riddle if you'd have asked that on which day the lotus increased its size by the half size of the pond, the answer would be 30th day same as the warm riddle which says on which day the warm eat exactly half number of leaves.

I don't think initial size matters here

[Harker]

Jumped in a little too early on that one. Great riddle.

[Kyanzes]

In case of the pond, it happens south of the equator so the coriolis force will cause the process to end sooner. In the case of the worm, it has to overcome the coriolis force of the northern hemisphere so it can only reach half on the last day. If we had a slightly weaker strong nuclear force then they would be equal. It can also be checked with the Pythagorean theorem because the partial pressure at eye level is not significant in relation to the annual number of sunny days in the vicinity of storm clouds.