Question

In a group of 15 people, 7 read French, 8 read English while 3 of them read none of these two. How

many of them read French and English Both?​

Answer 1

Answer:Group size = 15

No. of people who couldn’t read E (English) and F (French) both = 3

So new group size of people who speak E or F i.e. n(E U F) = 15 - 3 = 12

Now, n(E Union F) = n(E) + n(F) - n(E intersection F)

i.e. 12 = 8 + 7 - n(E intersection F)

So n(E intersection F) which is people who could speak both = 15 - 12 = 3 that’s the answer.

It can also be better explained with Venn diagrams in SET.

Hope it helps.