There are N questions in an exam. For i=1,2,3....,N, there are 2^(N-i) students who answered i or more questions wrongly. The total number of wrong answers is 8191. Find N.
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how many traingles can be formed if all sides have length in natural numbers and perimeter is 24?? guys I need a shortcut for these type of questions..

how many traingles can be formed if all sides have length in natural numbers and perimeter is 24?? guys I need a shortcut for these type of questions..

Along a road lie an odd number of stones placed at intervals of 10m. These stones have to be assembled around the middle stone. A person can carry only one stone at a time. A man carried out the job starting with the stone in the middle, carrying stones in succession, thereby covering a distance ...

Yeah its 31 only..middle stone will be 16th..then covering 15stones will take 2400 m..starting from last stone..and then repeating the same process will add upto 4800m.

There are three solutions of an acid − A, B and C − of different concentrations and volumes. The concentration of A in percentage points is an integer, that of B is 5 percentage points greater than that of A, while that of C lies between 60 and 80. If A and B are mixed, the resultant concentrati...

conc of A =x...then B=x+5..since the resultant conc is 25..therefore x+5>25 and x@hksparadox said..will be 73. when x=23...for rest values will be 41,57,89..

There are 5 chocolates which are to be shared by 3 persons. Find the number of ways of distributing the chocolates such that each of the persons get at least 1 chocolate.

Could any one please help :smiley: in solving the following problem..... :smiley:
Akshay is 16th from the left end in a row of boys and Vijay is 18th from the right end. Avinash is 11th from the Akshay towards the right end and 3rd from vijay towards the right end. How many boys are there...