Question

Let A and B be too sets containing four and two elements respectively then the number of subsets of set `AxxB` having atleast 3 elements is
A. 275
B. 510
C. 219
D. 256

Answer 1

Correct Answer - C
`n(A)=4,n(B)=2impliesn(AxxB)=8`
The number of subsets of `AxxB` having at least three elements
`=.^(8)C_(3)+.^(8)C_(4)+.^(8)C_(5)+...+.^(8)C_(8)`
`=2^(8)-(.^(8)C_(0)+.^(8)C_(1)+.^(8)C_(2))`
`=256-(1+8+28)=219`