Answer: Option C
Answer: (c)
Total number of students = 640 + 360 = 1000
Number of successful boys = 60% of 640 = 384
Number of successful girls = 80% of 360 = 288
Total number of successful students = 384 + 288 = 672
Number of unsuccessful students = 1000 – 672 = 328
Required percentage = ${328 × 100}/1000 = 32.8%$
Using Rule 25,
B = 640, G = 360, b = 60%, g = 80%
Percentage of passed students = $({Bb + Gg}/{B + G})%$
= ${640 × 60 + 360 × 80}/{640 + 360}$
= ${38400 + 28800}/1000 = 67200/1000 = 67.2%$
% of failed students = 100 – 67.2% = 32.8%