# Q22

#### Saumyojit

##### Full Member
<Link to commercial website removed>

what is the answer to this fifth question? three books one...
Table A --> top to bottom -->(3,2,1)
Table B---> First we need to bring out the no 1 book place it on table B , then we need to bring out no 2 book and hold it then we bring out third book and place it on the top of book 1 and then place no 2 book on the top of book 3

4 steps coming right?

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#### Dr.Peterson

##### Elite Member
Please don't make us go to a site to see what the problem is.

what is the answer to this fifth question? three books one...
Table A --> top to bottom -->(3,2,1)
Table B---> First we need to bring out the no 1 book place it on table B , then we need to bring out no 2 book and hold it then we bring out third book and place it on the top of book 1 and then place no 2 book on the top of book 3

4 steps coming right?
But I'm not even sure what it means.

#### Dr.Peterson

##### Elite Member
What is ur approach?
The first step, as I implied, is to translate the problem into English, which really means to ask the site to explain what you are allowed to do. How can you pick books up, and where can you set them down? Can you hold a stack in one hand while picking up another? And so on. Generally, I don't bother trying to solve problems that are so poorly written that I can't tell what is intended.

As for your proposed solution, you have to explain that, too. What do you mean by "bring out the no 1 book place it on table B", when they explicitly say "You can't remove the books from the middle of the stack"?

I can do it in 4 moves, but without fully understanding it, I can't say that it can't be done in less.

#### Saumyojit

##### Full Member
bring out the no 1 book place it on table B", when they explicitly say "You can't remove the books from the middle of the stack"?
Yes, when i bring out the no 1 book with my hand the last book not the middle book i am shifting it towards the other table .

And then there are only two books so i bring out the no 3 book from (3,2) stack and place it above book 1 and then book 2 above book 3.

SO 3 ways. New stack is (2,3,1)

#### Dr.Peterson

##### Elite Member
Yes, when i bring out the no 1 book with my hand the last book not the middle book i am shifting it towards the other table .
What does this mean? Please write more clearly.

SO 3 ways.
The question isn't about counting ways to do it, but the steps it takes. How about making a numbered list of the steps, each stated clearly.

#### Saumyojit

##### Full Member
First step is to bring out the book 1 and put it on the other table.
Next step is to bring out book 3 and place it on the other table.
Third step is to bring out book 2 and place it on the other table on the top of book 3 and book1

So, 3 steps

#### Otis

##### Elite Member
First step is to bring out the book 1 and put it on the other table
I'm not sure we're allowed to pull a book out from the bottom of a stack. The given note seems to imply that you first need to remove the top two books and set them aside. If so, then moving book1 to table B would be the second step.

PS: Their English contains a number of grammatical errors.

#### Saumyojit

##### Full Member
First step is to bring out the book 1 and put it on the other table.
Next step is to bring out book 3 and place it on the other table.
Third step is to bring out book 2 and place it on the other table on the top of book 3 and book1

So, 3 steps
@Otis @pka The answer is 4 but why the quoted text method is wrong?
Why can't we bring out book 1 at first ? it is not the middle book after all .

#### Dr.Peterson

##### Elite Member
@Otis @pka The answer is 4 but why the quoted text method is wrong?
Why can't we bring out book 1 at first ? it is not the middle book after all .
What does the problem say?

When they say you can't remove books from the middle, they obviously mean you can only take books (or, as I interpret it, stacks of books) starting at the top. It would be silly to say you can take the bottom book out but not the next book up.

But as we've said repeatedly, the problem is very poorly written, both in grammar (e.g. "books has to be moved") and in clarity. Ignore the problem!!!

#### Otis

##### Elite Member
it is not the middle book after all .
What if a stack had four books? How would you interpret that instruction?

Or, five books. Would you say the middle book could not be removed, but the book above or below it could?

#### Saumyojit

##### Full Member
What if a stack had four books? How would you interpret that instruction?

Or, five books. Would you say the middle book could not be removed, but the book above or below it could?

I would say the fifth book or the top most one and bottom most ... only two ends i am talking about

#### Otis

##### Elite Member
only two ends i am talking about
Very well then. You're talking about a special rule that has not been provided in the exercise statement. I'm sorry you were given garbage, but it happens.

Three steps is the correct answer, using your interpretation of the exercise. Good job!