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Question

The number of element in the power set P(S) of set S = {2, {1, 4}} is ?

The correct answer is

4

Set Elements Identification

The given set is represented as S = {2, {1, 4}}.

To find the number of elements in the power set P(S), we first need to identify the distinct elements within the set S.

The elements of set S are:

  • The number 2.
  • The set {1, 4}.

Therefore, the set S contains 2 distinct elements. Let's denote the number of elements in set S as '$n$'. So, we have $n = 2$.

Power Set Concept and Calculation

The power set of a set S, denoted as P(S), is the set containing all possible subsets of S, including the empty set (denoted as {} or $\emptyset$) and the set S itself.

A fundamental property of power sets is that if a set S has '$n$' elements, its power set P(S) will have $2^n$ elements (subsets).

In this case, since the set S = {2, {1, 4}} has $n = 2$ elements, the number of elements in its power set P(S) can be calculated using the formula:

Number of elements in P(S) = $2^n$

Substituting the value of $n=2$:

Number of elements in P(S) = $2^2$ = 4

Listing Subsets of S

To verify, let's list all the subsets of S = {2, {1, 4}}:

  • The empty set: {}
  • Subsets with one element: {2} and {{1, 4}}
  • Subset with two elements: {2, {1, 4}}

The power set P(S) is { {}, {2}, {{1, 4}}, {2, {1, 4}} }. Counting these subsets, we find there are exactly 4 elements in the power set P(S).

Conclusion

The number of elements in the power set P(S) of the set S = {2, {1, 4}} is 4.

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Important Questions from Set Theory and types of Sets

  1. If A is an open set and B is a closed set, then B - A is

  2. If P and Q be two sets such that P ∪ Q = P, then P ∩ Q will be

  3. A set containing n elements, has exactly ..... subsets.

  4. If P, Q and R are three sets, then which of the following is correct?

  5. Of the members of three athletic teams in a school, 21 are in the cricket team, 26 are in the hockey team and 29 are in the football team. Among them, 14 play hockey and cricket, 15 play hockey and football, 12 play football and cricket and 8 play all the three games. The total number of members in the three athletic teams is:

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