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In an examination there were 640 boys and 360 girls. 60% of boys and 80% of girls were successful. The percentage of failure was :
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- 20%
- 60%
- 30.5%
- 32.8%
Correct Option: D
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
| = | = 32.8% | 1000 |
Aliter : Using Rule 25,
B = 640, G = 360,
b = 60%, g = 80%
Percentage of passed students
| = |  |  | % | B + G |
| = | 640 + 360 |
| = | 1000 |
| = | = 67.2% | 1000 |
∴ % of failed students
= 100 – 67.2% = 32.8%
