75% of students of a class answered question No.1 correct and 55% answered Question No.2 correct and 20% answered neither question correctly. What percent of students answered both questions correctly?
সমাধান
সঠিক উত্তর: Option D
Students answered Q.-1 or Q.-2 or both correctly = (100-20) = 80%
Let, x% students answerd both correctly.
.:. (75-x) + (55-x) + x = 80
130-x = 80
.:. x= 50
