WAEC - Further Mathematics (2018 - No. 30)
Out of 70 schools, 42 of them can be attended by boys and 35 can be attended by girls. If a pupil is selected at random from these schools, find the probability that he/ she is from a mixed school.
\(\frac{1}{11}\)
\(\frac{1}{10}\)
\(\frac{1}{6}\)
\(\frac{1}{5}\)
คำอธิบาย
Let the number of mixed schools be S
The number of boys only = 42 - S
The number of girls only = 35 - S
(42 - S) + S + (35 - S) = 77 - S = 70
\(\implies\) S = 7
\(Probability = \frac{7}{70} = \frac{1}{10}\)