Here, `30%` students failed in English and `35%` failed in G.K.
`27%` students failed in both.
So, percentage of students that failed only in English `=30 - 27 = 3%`
Percentage of students that failed only in G.K. `=35 - 27 = 8%`
`:.` Percentage of students passed `= 100-(3+8+27) = 62%`
Let total number of students appeared in exam are `x`.
Then, `x**62/100 = 310`
`=> x = 310**100/62 = 500`
`:. 500` students appeared in the examination.