Combination
Q21.
What is the minimum number of ordered pairs of non-negative numbers that should be chosen to ensure that there are two pairs (a,b) and (c,d) in the chosen set such that a \equiv c mod 3 and b \equiv d mod 5Q22.
In how many ways can b blue balls and r red balls be distributed in n distinct boxes?Q23.
The number of 4 digit numbers having their digits in non-decreasing order (from left to right) constructed by using the digits belonging to the set {1, 2, 3} is____________.Q24.
The number of bit strings of length 8 that will either start with 1 or end with 00 is?Q25.
n couples are invited to a party with the condition that every husband should be accompanied by his wife. However, a wife need not be accompanied by her husband. The number of different gatherings possible at the party isQ26.
The number of binary strings of n zeros and k ones in which no two ones are adjacent isQ27.
m identical balls are to be placed in n distinct bags. You are given that m \geqkn, where k is a natural number \geq1. In how many ways can the balls be placed in the bags if each bag must contain at least k balls?Q28.
Choose the correct alternatives (More than one may be correct).The number of ways in which 5 A's, 5 B's and 5 C's can be arranged in a row is:Q29.
The number of substrings (of all lengths inclusive) that can be formed from a character string of length n is