Question 1192880:  A class of 30 students took two quizzes. Sixteen passed the first quiz and 20 passed the second. If 4 students failed both quizzes, how many passed both? 
 Answer by ikleyn(52903)      (Show Source): 
You can  put this solution on YOUR website! . 
A class of 30 students took two quizzes. Sixteen passed the first quiz and 20 passed the second.  
If 4 students failed both quizzes, how many passed both? 
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From the condition, 30-16 = 14 failed the first quiz, and
                    30-20 = 10 failed the second quiz,
             while           4 failed both quizes.
Hence,  the number of those who failed at least one quiz is  14 + 10 - 4 = 20.
It means that 30-20 = 10 students passed both quizes.    ANSWER
 
Solved.
 
 
 
 
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