Question

Let A be the set of primes less than 6 and B be the set of positive odd numbers less than 6. How many different sums of the form a + b are possible, if a is in A and b is in B?

Answer 1

A = {2,3,5} and B = {1, 3, 5}

2+1 =
2+3 =
2 + 5 =

3+1 =
3+3 =
3+5 =

5+1 =
5+3 = already have that
5+5 =

make sure you don't count equal sums twice,
e.g.
3+3 = 6
5+1 = 6
You are just looking at the different sums

Answer 2

=(1,2,3,4.....,18) A=(prime numbers)and B=(odd numbers greater than 3)IfA and B are subsets of the universal set .(a)Find the number of elements in And B. (b)Find the set (i)AnB (ii)n(AnB) (iii)AuB) (iv)n(AuB)