A class has two sections, which contain 20 and 30 students.

A class has two sections, which contain 20 and 30 students. The pass percentage of these sections are 80% and 60% respectively. The pass percentage of whole class is

Successful students in both classes

=	20 × 80	+	30 × 60	= 16 + 18 = 34
	100		100

∴ Required percentage

=	34	× 100 = 68%
	50

Or
Required percentage

=	20 × 80 + 30 × 60
	50

=	1600 + 1800	+	3400	= 68%
	50		50

Aliter : Using Rule 25,
Let us take B = 20, G = 30, b = 80%, g = 60%
∴ Required percentage

=	Bb+ Gg
	B + G

=		20 × 80 + 30 × 60			%
		20 + 30

=	3400	= 68%
	50