The pages of a book are numbered 0, 1, 2 . upto M, M>0. There are four categories of instructions that direct a person in positioning the book at a page. The instruction types and their meanings are :
1. OPEN : Position the book at page No. 1
2. CLOSE : Position the book at page No. 0
3. FORWARD, n :From the current page move forward by n pages; if, in this process, page number M is reached, stop at M.
4. BACKWARD, n : From the current page, move backward by n pages; if in this process, page number 0 is reached, stop at page number 0.
In each of the following questions, you will find a sequence of instructions formed from the above categories. In each case, let $$n_1$$ be the page number before the instructions are executed and $$n_2$$ be the page number at which the book is positioned after the instructions are executed.
FORWARD, 5; BACKWARD, 4. Which of the following statements about the above instructions is true?
For option A, put $$n_1$$ = 1, then $$n_2$$ will be 2 , hence equation won't hold true.
Now for option B, if we say M = 5 , then $$n_1$$ will be 0 and $$n_2$$ will be 1, hence equation won't hold true.
And equation in option D will not hold true too as put M = 5 , then $$n_1$$ will be 0 and $$n_2$$ will be 1.
Now in option C, equation is valid as put $$n_1$$ = 1 , then $$n_2$$ will be 2. Which is holding the equation valid too.
Hence our answer will be C.
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