CBSE Class 7 Answered

Qn. # 1

E = { 4,8,12,16,20,24,28 }

F= { 6 , 12 , 18 }

E F = { 12 }

--------------------------------------------------------

Qn.# 2

---------------------------------------------------

Qn. # 3

Number of elements in the set =  4

Number of sets with zero element ( null set ) = 1

Number of sets with one element = ⁴C₁ = 4

Number of sets with two elements = ⁴C₂ = 6

Number of sets with three elements = ⁴C₃ = 4

Number of sets with four elements = 1

Hence total number of subsets  =  1 + 4 + 6 + 4 +1 = 16

Proper subset = 15

---------------------------------------------------------------------

Qn#4

if two sets of voters of respective contestants are disjoint , then

x + (x+20) + 20 = 100

hence x = 30

-------------------------------------------------

Qn. # 6

A = { 2,3,5,7,11,13,17,19 }

B = { 1,4 }

A and B are disjoint sets

---------------------------------------

Qn. 7

2 is only number that is even and prime .

A B = { 2 }

---------------------------------------

Qn. #8

-------------------------------------------------------

Qn. #9

P = { 3, 6, 9, 12 .............93, 96, 99 }

Q = { 10, 20, 30, 40, 50 , 60 , 70 , 80, 90 }

P Q = { 30 , 60, 90 }

Hence only true statement is

P Q = { x | x is multiples of 30 and < 100 ; x ∈N }

------------------------------------------

Qn.#10

P = { 2,4,6,8  ....................... }

Q = { 2 , 4, 8 , 16 ,  .................}

hence Q ⊂ P

------------------------------------------------

Qn.#11

Shaded area is common to A , common to C but not overlapping with B

Hence shaded area represents A ∩ B' ∩ C