topic – RBR

Permutation-and-Combination

Please wait while the activity loads.
If this activity does not load, try refreshing your browser. Also, this page requires javascript. Please visit using a browser with javascript enabled.

If loading fails, click here to try again

Question 1

A	P = Q - k
B	P = Q + k
C	P = Q
D	P = Q +2 k

Engineering-Mathematics Permutation-and-Combination Gate-2008

Question 1 Explanation:

P=1+3+5+7+...+(2k-1)
=(2-1)+(4-1)+(6-1)+(8-1)+...+(2k-1)
=(2+4+6+8+...+2k)+(-1+-1+-1+k times)
=Q-(1+1+...+k times)
=Q-k

Question 2

The number of substrings (of all lengths inclusive) that can be formed from a character string of length n is

A	n
B	n²
C
D

Engineering-Mathematics Permutation-and-Combination Gate-1994

Question 2 Explanation:

No. of substrings of length
n = 1
(n-1) = 2
(n-2) = 3
So, Total = n(n+1)/2

There are 2 questions to complete.