Question

There are 12 pupils in a class.

Answer 1

Answer:

Step-by-step explanation:

Just look at the picture

Answer 2

Answer:

The value in box of circle B is 3 and the value in box which belongs in both circle B and S is 6 and value which belongs in circle S is 1 and the value of box outside both the circle is 2.

Step-by-step explanation:

In given Venn diagram

ε = class of 12 pupils

pupils who have brother B = 9

pupils who have sister S = 7

pupils who have neither brother nor sister = 2

Hence the Venn diagram is drawn in the attachment for your reference.

n(E) =12

n(neither B nor S) = 2

So, n(B or S)= n(E) - n(neither B nor S)= 12-2=10

n(B) = 9

n(S) = 7

Now, addition theorem,

n(B or S) = n(B) + n(S) - n(B and S)

$10=9+7-n(B\ and \ S)\\n(B\ and \ S) = 6$

So the value in box which is in both circle B and S is 6.

So the Box which contains only brothers = n(B) - n(B and S)  = 9 - 6 = 3

Value in box of circle B is 3.

So the Box which contains only Sisters = n(S) - n(B and S)  = 7 - 6 = 1

Value in box of circle S is 1.