NDA 2018 Maths · Mathematics · Sets, Relations and Functions · easy

If A has 2 elements, what is the number of elements in the power set of the power set of A, that is n(P(P(A)))?

Single correct option

A

has 2 elements, what is the number of elements in the power set of the power set of

A

, that is

n(P(P(A)))

Show answer and solution

Answer: (B) 16

n(P(A))=2^2=4

, so

n(P(P(A)))=2^4=16

. The common slip is to stop after one power set (giving 4) or to compute

2^{2\cdot 2\cdot 2}

instead of applying the power set twice, which gives 8.

Original question written in the NDA 2018 Maths pattern and checked twice for the correct answer. Not an official question paper. How we write and check questions · Corrections policy · Report a mistake