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75% of students of a class answered Question No. 1 correct and 55% answered Question No. 1 correct and 20% answered neither question correctly . What percent of students answered both question correctly ?

75% of students of a class answered Question No. 1 correct and 55% answered Question No. 1 correct and 20% answered neither question correctly . What percent of students answered both question correctly ? Correct Answer 20%

Students answer Q.1 or Q.2 or both correctly = ( 100 - 20) = 80% Let, x% students answered both correctly ( 75 - x) + ( 55 - x) + x = 80 130 - x = 80 x = 50

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