Question

Of the candidates who sat for an international mathematics examination, 18% of the candidates obtained
grade A. 38% obtained grade B and the rest obtained grade C. Given that 77 candidates obtained grade C.
find the total number of candidates who sat for the examination.​

Answer 1

Answer:

175

Step-by-step explanation:

let ,x candidates sat for the exam

$18\% \: of \: x \: is = x \times \frac{18}{100} \\ = \frac{9x}{50 } \\ 38\% \: of \: x \: is = x \times \frac{38}{100} = \frac{19x}{50} \\ accordingly \\ x - ( \frac{9x}{50} + \frac{19x}{50} ) = 77 \\ x - ( \frac{9x + 19x}{50} ) = 77 \\ x - \frac{28x}{50} = 77 \\ \frac{50x - 28x}{50} = 77 \\ 22x =3 850 \\ x = \frac{3850}{22} \\ x = 175$

there for,total 175 candidates sat for the exam