10. One sixth of an audience in a children's theatre are adults. Two fifths of the children are boys. What fraction of the audience are girls?
A $\frac{1}{2}$
B $\frac{1}{3}$
C $\frac{1}{4}$
D $\frac{1}{5}$
E $\frac{2}{5}$
10. A One sixth of the audience are adults. Therefore five sixths of the audience are children. Two fifths of the children are boys and hence three fifths of the children are girls. Therefore three fifths of five sixths of the audience are girls. Now $\frac{3}{5} \times \frac{5}{6}=\frac{1}{2}$. Hence the fraction of the audience who are girls is $\frac{1}{2}$.