SETS-6

In Bibanja district the number of people who speak Kiswahili or Lingala is 400. 200 of them speak Kiswahili and 300 of them speak Lingala. How many speak both languages?

solution

In most cases, OR stands for union whereas AND/BOTH, stands for intersection.

Let Kiswahili=n(K), Lingala= n(L).

n(K)= 200 ,

n(L)= 300,

n(KuL) = 400,

n(KnL)=?

n(KuL) = n(K) + n(L) - n(KnL)

400  =  200 + 300 – n(KnL)

400  =  500 – n(KnL)

n(KnL) =  500 – 400

n(EnF) =  100

Hence n(EnF)=100 answer