Question

$37\frac{1}{2}$% of the candidates in an examination were girls, 75% of the boys and $62\frac{1}{2}$% of the girls passed and 342 girls failed The number of boys failed was

• A. 350
• B. 360
• C. 370
• D. 380

Answer 1

The correct option is D 380

Let the total number of candidates be x
Than$(100-62\frac{1}{2})$% of $37\frac{1}{2}$% of x=342
$\frac{75}{2}\times \frac{1}{100}\times \frac{75}{2}\times \frac{1}{100}\times x=342$
$x=\frac{342\times 64}{9}=2432$
Number of boys failed=(100-75)% of $(100-37\frac{1}{2})$% of 2432
$=\frac{25}{100}\times \frac{125}{2}\times \frac{1}{100}\times 2432=380$