The number of students in a class is 75, out of which $$33\frac{1}{3}\% $$  are boys and the rest are girls. The average score in mathematics of the boys is $$66\frac{2}{3}\% $$  more than that of the girls. If the average score of all the students is 66, then the average score of the girls is:

Solution (By Examveda Team)

$$66\frac{2}{3}\% \to \frac{{ + 2}}{3}$$
\[\begin{array}{*{20}{c}} {}&{1\,\,\,\,\,\,\,\,\,\,:\,\,\,\,\,\,\,\,\,\,2} \\ {{\text{Average}} \to }&{5a\,\,\,\,\,\,\,\,:\,\,\,\,\,\,\,\,3a} \\ {}&{\overline {\,\,5a + 6a = 3 \times 66\,\,} } \\ {}&{11a = 3 \times 66} \\ {}&{a = 18} \end{array}\]
Average of girls = 3a = 3 × 18 = 54