test_series

Question

I think answer is 112

Comments

how u got 112?

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120 is correct. 2^2n represents total number of comparisons to be performed between two n-bit numbers. 2^n represents where A=B. A<B and A>B has same number of cases and thus divided by 2.

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yes you r correct. i did mistake in calculation.

Answer 1

A and B are two 4 bit numbers. Range of both A and B is 0-15 (in decimal). Hence, if we write it like this:

A: 0 ,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15   and

B: 0 ,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15

For each number in row A, how many numbers in row B are less than that number? For example, 1 in row A is less than only 0 of row B. Similarly, 4 of row A is less than 0,1,2,3 of row B. So what is the total number of numbers for which every number in row A is less than some number of row B? It is simply, 1+2+3+4+...+15=15*16/2=120.  Hence option (A)

P.S. : I hate remembering non-standard pesky formulas.