The average weight of a class dropped from $65$ kg to $62$ kg when a student weighing $77$ kg was out of the class. How many students are there in the class now?

Let $A=\frac{1^{13}+2^{13+}{3}^{13}+....+{100}^{13}}{100}, B=\frac{1^{13}+3^{13}+5^{13}....+{99}^{13}}{50}, C=\frac{2^{13}+4^{13+}{6}^{13}+...+{100}^{13}}{50}$

Which of the following is true?

The diagram shows a square quilt that is made up of identical squares and two sizes of right-angled triangles. What percentage of the quilt is shaded?