Question

It was observed that 60% read

magazine A, 50% magazine B, 50% magazine C, 30% A and B, 20% B and C, 30% C and
A and 10% all the threes. In the fitness of the thing, state (i) what percentage read exactly
two magazines ? (ii) what percentage do not read any of the threes ?

Answer 1

je

Explanation:

suis suis pasforet en anglais

Answer 2

We're dealing with percentage. hence, our universal set: U=100%.

Let:A = set of those that read magazine A

B = set of those that read magazine B

C = set of those that read magazine C

(i) we are looking for n{(A n B) u (B n C)}

so, n{(A n B) u (B n C)} = n(A n B) + n(B n C) -n(A n B n C)

n{(A n B) u (B n C)} = 20% + 30% - 10%

: n{(A n B) u (B n C)} = 40%

(ii) We're looking for {A' n B' n C'}

{A' n B' n C'} = n(U) - n(A u B u C)

{A' n B' n C'} = 100% - n(A u B u C)

n(A u B u C) = n(A) + n(B) + n(C) - n{(A n B) - n(A n C) -n(B n C) + n(A n B n C)

n(A u B u C) = 60% + 50% + 50% -30% - 30% - 20% + 10%

n(A u B u C) = 90%

however, {A' n B' n C'} = 100% - n(A u B u C)

: {A' n B' n C'} = 100% - 90%

{A' n B' n C'} = 10%

let me know if you think there's a reason to doubt my answer.