In an examination, 35% of the candidates failed in Mathematics, 25% failed in Science and 10% failed in both subjects. If 250 candidates passed in both subjects, how many candidates appeared in the examination?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 500
A candidate who passed in both subjects is one who failed in neither. First find the per cent who failed in at least one subject: those who failed in both are counted in both failure figures, so they are subtracted once.
Failed in at least one subject \(=35\%+25\%-10\%=50\%\)
Passed in both subjects \(=100\%-50\%=50\%\)
\(50\%\) of the candidates \(=250\)
Candidates \(=\displaystyle\frac{250\times 100}{50}=500\)
