SET THEORY

Let A = {3, 6, 9, 12, 15} and B = {4, 8, 12, 16}. Which of the following is true about the two sets?

• 
  

  $A\cup B=\left\{12\right\}$

• $A\cap B=\left\{3,\ 4,\ 6,\ 8,\ 9,\ 12,\ 15,\ 16\right\}$

• $A-B=\left\{3,\ 6,\ 9,\ 15\right\}$

• $A-B=\left\{4,\ 8,\ 16\right\}$

The set S = {fever, dry cough, tiredness} list the common symptoms of COVID-19. What is the cardinality of this set?

• 3

• 4

• 5

• 6

What is the cardinality of  $\phi$  ?

• 0

• 1

• Empty set

• None

If T = {different types of triangles} and Q = {different type of quadrilaterals}, then which of the following is the most suitable for Universal set?

• U = {x | x is a plane figure}

• U = { x | x is a shape}

• U = { x | x is a polygon}

• U = { x | x is a figure}

Let K be the set of the letters in the sentence 'Keep safe'. How do you write this set correctly using the Roster Method?

• K = {k, e, e, p, s, a, f, e}

• K = {k, e, p, s, e, f}

• K = {k, e, e, p, s, a, f}

• K = {k, e, p, s, a, f}

Which of the following cannot be considered a subset of H = {h, e, a, l, t, h, y}?

• W = {h, e, a, l, t, h, y}

• M = { }

• F = {h, e, a, t}

• R = {h, e, a, r, t}

Which of the following is not an element of the set V = { 3x | x is a counting number from 3 to 9 }

• 3

• 9

• 15

• 21

What is the cardinality of the set W = {0, 1, 2, 3,...100}?

• 5

• 6

• 100

• 101

How many subsets does the set L = {l, o, v, e} have?

• 4

• 6

• 8

• 16

Let O = {1, 3, 5, 7, 9, 11, 13, 15} and P = {1, 2, 3, 5, 7, 11, 13}. Find  $O-P$  .

•  $O-P=\left\{1,\ 2,\ 3,\ 5,\ 7,\ 9,\ 11,\ 13,\ 15\right\}$  

•  $O-P=\left\{1,\ 3,\ 5,\ 7,\ 11,\ 13\right\}$  

•  $O-P=\left\{9,\ 15\right\}$  

•  $O-P=\left\{2\right\}$