Maths-
General
Easy
Question
A is a set containing n elements. A subset P of A is chosen. The set A is reconstructed replacing the elements of P. A subset Q of A is again chosen. The number of ways of choosing P and Q so that P Q contains exactly two elements is-
- 9. nC2
- 3n–2. nC2
- 2. nCn
- None of these
The correct answer is: 3n–2. nC2
Related Questions to study
Maths-
There are p points in space, no four of which are in the same plane with the exception of q points which are all in the same plane. The number of different planes determined by the points is-
There are p points in space, no four of which are in the same plane with the exception of q points which are all in the same plane. The number of different planes determined by the points is-
Maths-General
Maths-
The number of ways to fill each of the four cells of the table with a distinct natural number such that the sum of the numbers is 10 and the sums of the numbers placed diagonally are equal, is-
The number of ways to fill each of the four cells of the table with a distinct natural number such that the sum of the numbers is 10 and the sums of the numbers placed diagonally are equal, is-
Maths-General
Maths-General
Maths-
Two teams are to play a series of 5 matches between them. A match ends in a win or loss or draw for a team. A number of people forecast the result of each match and no two people make the same forecast for the series of matches. The smallest group of people in which one person forecasts correctly for all the matches will contain n people, where n is-
Two teams are to play a series of 5 matches between them. A match ends in a win or loss or draw for a team. A number of people forecast the result of each match and no two people make the same forecast for the series of matches. The smallest group of people in which one person forecasts correctly for all the matches will contain n people, where n is-
Maths-General
Maths-
The number of ways in which, 2n things of one sort, 2n things of another sort and 2n of a third sort can be divided between two person so that each get 3n things is -
The number of ways in which, 2n things of one sort, 2n things of another sort and 2n of a third sort can be divided between two person so that each get 3n things is -
Maths-General
Physics-
The current passing through a choke coil of 5 henry is decreasing at the rate of. The e.m.f. developing across the coil is
The current passing through a choke coil of 5 henry is decreasing at the rate of. The e.m.f. developing across the coil is
Physics-General
Physics-
The energy stored in an inductor of self inductance henry carrying a current of 1 A is
The energy stored in an inductor of self inductance henry carrying a current of 1 A is
Physics-General
Maths-
If and then the smallest positive values of and respectively, are
If and then the smallest positive values of and respectively, are
Maths-General
Maths-
Let be a positive integer such that Then
Let be a positive integer such that Then
Maths-General
Maths-
In triangle if and, then is equal to
In triangle if and, then is equal to
Maths-General
Maths-
If where then is equal to
If where then is equal to
Maths-General
Maths-
The number of solutions of is
The number of solutions of is
Maths-General
Maths-
In a set of teachers of a school, two teachers are said to be related if they “teach the same subject”, then the relation is
In a set of teachers of a school, two teachers are said to be related if they “teach the same subject”, then the relation is
Maths-General
Maths-
If and is the universal set, then is
If and is the universal set, then is
Maths-General
Maths-
In the set a relation is defined by Then, is
In the set a relation is defined by Then, is
Maths-General
Maths-
Consider the set of all determinants of order 3 with entries 0 or 1 only. Let be the subset of consisting of all determinants with value 1. Let C be the subset of the set of all determinants with value Then
Consider the set of all determinants of order 3 with entries 0 or 1 only. Let be the subset of consisting of all determinants with value 1. Let C be the subset of the set of all determinants with value Then
Maths-General