WAEC - Mathematics (1999 - No. 7)
A group of 11 people can speak either English or French or Both. Seven can speak English and six can speak French. What is the probability that a person chosen at random can speak both English and French?
\(\frac{2}{11}\)
\(\frac{4}{11}\)
\(\frac{5}{11}\)
\(\frac{11}{13}\)
คำอธิบาย
Let the number of people that speak both English and French = x
Then (7 - x) + x + (6 - x) = 11
13 - x = 11 \(\implies\) x = 2.
\(\therefore\) P(picking a person that speaks both languages) = 2/11